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INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


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BY 


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w. R. GREGG, in charge Aerological Division, 

ASSISTED BY 

-Messrs. V. E. JAKL, W. S. CLOUD, L. T. SAMUELS, and R. C. LANE. 


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Return this book on or before the 
Latest Date stamped below. A 
charge is made on all overdue 
books. 

University of Illinois Library 


FEB 2 3 


MAR 1 1 







W. B. 740. 

U. S. DEPARTMENT OE AGRICULTURE, 
WEATHER BUREAU. 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


BY 


W. R. GREGG, in charge Aerological Division, 

ASSISTED BY 

Messrs. V. E. JAKL, W. S. CLOUD, L. T. SAMELS, and R. C. LANE. 


Prepared under direction of 
C. F. MARVIN, Chief U. S. Weather Bureau. 



WA8HINQTON; 

UOVEKNMENT PIUNTXNQ OFFIOK. 
1021. 


Digitized by the Internet Archive 
in 2017 with funding from 

University of Illinois Urbana-Champaign Alternates 


https://archive.org/details/instructionsfora00unit_3 


TABF.E OF CONTENTS. 


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Introduction 

Part I. The Use of Kites 

1. Selection and establishment of a kite station.. 

2. Kite reel house 

3. Kite reel and motor 

Protection against lightning 

4. Kite wire 

Splicing the wire 

5. Kites and kite making 

Marvin-Hargravs kite 

Material required for standard size kite 

High wind kite 

Light wind kite 

G. Meteorograph 

Pressure element 

Temperature element 

Humidity element 

Wind element 

Record sheet 

Clock cylinder 

Case or cover 

7. Calibration of meteorographs 

Pressure test 

Temperature test 

Humidity test 

Wind test 

Time test 

Lengths of pen arms and centers of arcs 

Reduction of the tests; Pressure 

Temperature 

Temperature effect on pressure element 

Humidity 

Time rate 

Wind 

8. Making the flights 

Carrying the kites 

Care of meteorograph 

Launching the kites 

Landing the kites 

Kite wire 

Oijservation and experience 

When to reel in 

Number of kites to use 

Weather types 

Clouds 

Diurnal series 

Thunderstorms 

Local conditions 

Breakaways 

9. Reducing records for telegraphic message 

10. Final reduction of records 

Hour lines 

Base lines 

Placing and computing levels 

Hypsometric equation 

Tabulation 

11. Reduction tables 

Determination of heights by the barometer. 

Temperature-correction factor 

Humidity correction 

Correction for wind velocity 


Page. 


7 

8 
9 

10 

10 

11 

12 

12 

16 

16 

17 

17 

18 
18 
19 
19 

19 

20 
20 
20 
21 
22 
22 
23 
23 
23 
26 
26 
26 
28 
28 
29 
29 

29 

30 

30 

31 

31 

32 

32 

33 
3r> 
36 

36 

37 
37 

37 

38 

39 

39 

40 

43 

44 

46 
4C 

47 

48 

49 


Part I. The Use op Kites— C ontinued. 

11. Reduction tables — Continued. 

Pressure of acjueous vapor 

Relative humidity 

Part II. The Use of Pilot Balloons 

1. Selection of stations and observation points 

2. Theodolite 

Assembling the theodolite 

Care of the theodolite 

Packing the theodolite 

Carrjdng the theodolite 

Adjustments of the theodolite 

Setting up theodolite for observation 

Determination of north-south line 

First method 

Second method 

Third method 

Orientation of theodolite 

3. Balloons 

Color 

Patching leaky balloons 

Size 

Weighing 

Inflation 

Sealing 

Measuring 

4. JIaking an observation 

Single-theodolite observations 

Double-theodolite observations 

Omi.«sion of an ascension 

5. Computation 

Method I. (1) Single-theodolite computation, slide- 

rule method 

Plotting or tlie construction of the horizontal projec- 
tion 

Method I. (2) Single-theodolite, graphical method . . 
Method 1. (3) Single-theodolite, slide-rule computa- 
tion, graphical cosine plotting 

Method I . (4) Single-theodolite, kigarithmic coinjiuta- 

tion 

Double-theodolite computation 

Method II. (1) Double-theodolite, graphical method . 
Method II. (2) Double-theodolite, graphical method. 
Method II. (3) Double-theodolite, graphical method. 
Method II. (4) Double-theodolite, logarithmic 
method 

6. Reduction of data 

7. Coding the message 

No ascension 

Code for time and date word.s 

Code for wind aloft report 

Code for altitude 

Code for clouds 

Code for visibility 

8. Forms and roduction tables 

Rate of a.scent in in. p. m 

.Altitude — time tables for various rales of ascent 

Free lift for delinite inflation 

Temperature-conversion table 

.Miles per hour into meters per second 

Inches into millibars 


IL-igC 


50 

51 
55 
55 

57 

58 

59 

60 
60 
60 
62 
63 

63 

64 

65 

66 
66 
66 

67 

68 
68 
68 

69 

70 
70 

74 

75 
77 

77 

78 

79 
81 

81 

82 

82 

82 

82 

83 

84 
86 
93 

95 

96 

97 
105 
105 
107 
107 
109 

114 

115 
115 
115 
115 


3 


1569 i 


LIST OF ILLUSTKATIONS. 


% 


Page. 


Fig. 1. Plot showing the position of buildings and kite field at 

Ellendale Aerological Station 8 

2. Front view of office and kite storage building at Broken 

Arrow Aerological Station 8 

3. Close view of kite-reel house at Ellendale Aerological 

Station 8 

4. Right front view of kite reel 9 

5. Left front \dew of kite reel 8 

6. View of rear of kite reel; also of variable-speed motor... 9 

7. Method of attaching copper cable to main “ground” 

pipe 9 

8. Method of attaching copper ware to “ground” pipes 

placed at stated intervals around the periphery of the 
reel house 10 

9. Method of splicing Idte wire by means of “ large twister ” . 10 

10. Method of turning end of loose wire around main wire 

by means of “ small twdster ” 11 

11. One method of reeling wire from the kite-reel drum to 

a smaller drum 11 

12. Different sizes of box kites used at aerological stations. . 12 

13. Front or bridle face of a kite 13 

14. Central or bridle truss of a kite 14 

15. One of the side trusses of a kite 14 

16. Isometric \Tiew of a kite 15 

17. Method of making joints, attaching bridle, etc 16 

18. Metal angles used in fastening principal joints 16 

19. Metal angles for intermediate joints 16 

20. Position and method of attachment of meteorograph in 

a kite 12 

21. Front view of Marffin kite meteorograph 18 

22. Rear view of Marvin kite meteorograph 19 

23. End view of Marvin kite meteorograph 18 

24. Horizontal screening tube in kite meteorograph, show- 

ing method of mounting hairs of hygrometer 1 8 

25. Calibration or test of the different elements in a kite 

meteorograph 24 

26. Pressure scale values for meteorograph, as determined 

from tests 25 


Page. 


Fig. 27. Curve showing humidity scale values for different 

humidities 27 

28. Arbitrary or measuring scale; Large divisions corres- 

pond to divisions on meteorograph sheet 27 • 

29. Percentage scale, used with scale in figure 28, for de- 

termining values of relativ^e humidity for any ordi- 
nate on meteorograph sheet 27 

30. Time scale for use with kite meteorograph 28 

31. Proper method of holding a kite preparatory to launch- 

ing it 30 

32. Typical meteorograph record of a kite flight 39 

33. Diagram showing method of determining the mean tem- 

perature of the air column 44 

34. Section of observation platform and theodolite stand, 

showing the insulation of the one from the other 57 

35. Theodolite used in kite and balloon work 58 

36. Theodolite vernier 58 

37. Section of theodolite showing arrangement of V'erniers 

with horizontal and vertical circles 59 

38. Proper method of carrjdng theodolite; and insulation 

of theodolite stand from observ'ation platform 60 

39. Collimation adjustment 61 

40. Effect of prism on line of sight 61 

41. Horizontal axis adjustment 62 

42. Peg adjustment 62 

43. Constellations of Ursa Major and Cassiopeia 64 

44. Balloon filling apparatus used for “definite” inflation. . 70 

45. Single-theodolite plotting board 80 

46. Plan of double-theodolite plotting board 83 

47. Plan of triangulatiou showing rclativ'e positions of 

balloon 85 

48. Section of plotting board, showing setting of horizontal 

projection for determination of direction and ve- 
locity 88 

49. Graphing board for construction of Form No. 1115- .\er. 89 

50. Sampleof velocity-direction graph. Form No. 1115-Aer. 90 

51. Graphical representation of wind-words of balloon code. 94 


4 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


INTRODUCTION. 


The value of free-air data is now universally recognized. 
Until a comparatively recent date these data were used 
ver}^ largely in studies whose purpose was to add to our 
knowledge of the characteristics of the free air in relation 
to latitude, topography, and different conditions of 
weather at the earth’s surface. At some places monthly, 
seasonal, annual, and, to a less extent, diurnal values 
have been fairly well determined to considerable alti- 
tudes, and some important conclusions as to the changes 
in free-air conditions accompanying marked changes in 
those at the surface have likewise been reached. In 
general, however, it can truthfully be said that aero- 
logical investigations are stiff in what may be called the 
"pioneer” stage. Immense expansion of the work is 
necessary before our knowledge of free-air conditions is 
at all comparable to that of surface conditions, i^d 
even the latter is as yet far from complete, for most parts 
of the earth. 

During the past few years the practical application of 
free-air data has come very decidedly to the front. For 
this the World War and the rapid development of avia- 
tion are largely responsible. Average values, though 
constituting important information, are no longer suffi- 
cient. It is now necessary to know the current condi- 
tions. Densities are required in ballistics, and wind di- 
rection and force in both ballistics and aviation. More- 
over, free-air and surface conditions are so closely related 
that a study of the two, observed simultaneously and 
over widely distributed areas, can not fail to increase the 
accuracy of forecasts, not only of conditions in the higher 
strata, but of surface weather as well. It becomes there- 
fore increasingly important that this work be developed 
as rapidly and as thoroughly as possible. 

Aerological investigations are con<luctcd for the most 
part by means of kites, pilot balloons, and sounding bal- 
loons. In the past small captive balloons have been 
used in calm weather, but because of difficulty of secur- 
ing good ventilation and because, moreover, low altitudes 
only could be reached, this method has been largely dis- 
continued. Manned balloons and kite balloons have also 
been used, but these are too expensive for ordinary pur- 
poses. Undoubtedly the airplane offers a means of ex- 
ploring the air in a meteorological sense, and will in the 
future be adapted to this use. Before this is done, 
however, it will be necessary to work out certain details 
of equipment, instrumental exposure, etc. 

Kites enable us to observe atmospheric pressure, tem- 
perature, humidity, wind, and electric potential at vari- 


ous altitudes up to 5 or 6 kilometers, but the average 
height reached is a little less than 3 kilometers. Kites 
can not be flown in very light or very strong winds, nor 
are they successfully used during stormy weather; never- 
theless, the percentage of days on which kites are flown 
is high, being about 93 for 5 years’ work at Drexel, 
Nebr. Pilot balloons give us wind conditions only; they 
can be used in weather unfavorable for kites, i. e., in 
gales or light winds, but, on the other hand, can not be 
observed in clouds or during other conditions of poor 
visibility. By means of sounding balloons we obtain 
valuable data, including pressure, temperature, humid- 
ity, and wind, at much greater heights than can be 
reached by kites. These data, however, are not imme- 
diately available, as several days are necessary as a rule 
for the recovery and return of the balloons. In this re- 
spect kites and pilot balloons are decidedly superior, 
since the records can be used at once for the information 
of the forecasters and others. It is evident that all three 
methods have limitations, to which due consideration 
must always be given in discussing the results. 

In order to obtain reliable data it is necessary for the 
observers, computers, and others to become familiar 
with a mass of details as to construction, care, and use 
of apparatus; difficulties to be overcome in getting the 
best possible records; and reduction and interpretation 
of the results. Aerological investigations have been con- 
ducted by the Weather Bureau more or less reguhirly for 
nearly 25 years. From the experience thus gained much 
has been learned, but up to the present time this knowl- 
edge has for the most part been transmitted orally, 
although instructions covering certain features of the 
work have been furnished from time to time in type- 
written or printed form. The purpose of this pamphlet 
is to bring together all necessary information in suffi- 
cient detail to enable those wholly unacquainted with the 
work to become efficient aerological observers and com- 
puters. These instructions are confliu'd entirely to work 
with kites and pilot balloons, since sounding balloons can 
not be used for some time to come, owing to lack of funds, 
and, besides, several changes in methods and equipment 
are contemplated. 

These instructions are in part original and in part 
have been prepared from the following sources: 

“Kite Experiments at the Weather Bureau,” by C. F. 
Marvin, W. B. 110, 1890. 

“Instructions for Aerial Observers,” by C. F. Marvin. 
Circular K, Weather Bureau, 1898. 


6 


6 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


"The Methods and Apparatus Used in Obtaining Upper 
Air Observations at Mount Weather, Va.,” by Wm. R. 
Blair. Bulletin oj the Mount Weather Ohservatory, yo\. 1, 
pp. 12-19, 1908. 

“The Construction of a Weather Bureau Kite,” by 
A. J. Henry. Bulletin oj the Mount Weather Observatory , 
vol. 2, pp. 227-236, 1910. 

“ The New Kite Reel,” by Wm. R. Blair. Bulletin oj the 
Mount Weather Observatory, vol. 1, pp. 237-238, 1908. 

“Improved Kite Hygrometer and Its Records,” by 
W. R. Gregg. Monthly Weather Review, vol. 45, pp. 153- 
155, 1917. 

“The Use of a Flag Pole in Calibrating Kite Anemome- 
ters and Also for Observing at Close Range the Behavior 
of Kites in the Ah’,” by B. J. Sherry. Monthly Weather 
Review, vol. 44, p. 327, 1916. 

“Notes on Kite Flying,” by V. E. Jakl. Monthly 
Weather Review Supplement No. 13 (Aerology No. 8), 
pp. 7-12, 1918. 

“Instructions for Operation of Aerological Stations, 2d 
Order,” issued in typewritten form by Meteorological 
Service, United States Signal Corps, 1918. 


“Instructions to Observers in Field Kite Work,” is- 
sued in typewritten form by Aerological Division, 
Weather Bureau. 

In the preparation of these Instructions special men- 
tion is due Mr. V. E. Jakl, who has contributed sections 
5, 8, and 9 of Part I; Messrs. W. S. Cloud and L. T. 
Samuels, sections 6, 7, and 10 of Part I; and Mr. R. C’ 
Lane, who has written the major portion of Part II. 
Numerous helpful suggestions offered from time to time 
by various members of the field and Central Office force 
of the Aerological Division; by Mr. S. P. Fergusson, of the 
Instrument Division; and by Maj. Wm. R. Blair and 
Capt. B. J. Sherry, of the Meteorological Section, Signal 
Corps, have been incorporated in the Instructions. Ac- 
knowledgment is also due Mr. Roy N. Covert for fur. 
nishing specifications, with drawings (figs. 7 and 8), for in- 
stallation of kite reel to insure protection against light- 
ning (in Part I, section 3) ; and to Mr. Wm. C. Haines, 
who furnished instructions, with drawings (figs. 39, 40, 
41, and 42), for adjustments of the theodolite (in Part II, 
section 2) . — IP. R. Gregg. 


PART 1 . THE USE OF KITES. 


1. SELECTION AND ESTABLISHMENT OF A KITE STATION. 

Sites for kite stations must be chosen with considerable 
care. Experience has shown that the best location is 
one in level country rather than on a mountain top, the 
latter being undesirable because of its influence on the 
meteorological elements and the resulting erroneous rela- 
tions indicated between the surface and free-air condi- 
tions. The country surrounding a kite station should 
be as free as possible from forested tracts, lakes, marshes, 
rivers, etc.; also, from toivns, steam and electric railways, 
and high-tension power lines. Inasmuch as free-air 
winds in this country blow for the most part from some 
westerly direction, it is essential that there should be as 
few as possible of the undesirable features above men- 
tioned on the east side of the station. Fairly good roads 
are necessary in order that kites that have broken away 
may be readily recovered. In many respects kite flying 
can be carried on most effectively if the station is com- 
pletely isolated, so far as centers of population are 
concerned, but, on the other hand, difficulties of trans- 
portation, of procuring power and lights, and of providing 
good living conditions for the men render such a location 
inadvisable. As a compromise the Weather Bureau 
therefore selects sites with open country to the east, but 
with a small town (1,000 to 2,000 people) approximately 1 
kilometer to the west. The plot used as a kite field is 
usually square and contains 40 acres of land, as nearly 
level as possible, cleared of trees, stumps, etc., and sur- 
rounded by a sufficiently strong fence to keep out live 
stock. In case there are telegraph, telephone, or high- 
tension lines within a distance of 2 or 3 kilometers to the 
north, east, or south, an extra “guard” wire is installed 
about 1 foot above the service wires. Bower and lights 
are furnished from the town plant to the station by means 
of underground circuits. All buildings, except the reel 
house, and all surface instrumental equipment are located 
in such part of the western side of the field as is most 
readily accessible from the town. The instrument 
shelter, wind tower, etc., are installed in accordance with 
instructions issued by the Instrument Division. Figure 
1 shows the customary arrangement of buildings and 
instrumental equipment, as well as the location of the 
kite field with res[)ect to the adjacent town. 

The geographic coordinates of the stations are deter- 
mincal in the same way as for all other Weather Bureau 
stations. Latitude and longitude can be found for many 
places in bulletins of the Geological Survey, Lippincott’s 
Gazetteer, and other publications. The data from these 
sources are used, after verification as to their accuracy 
by reference to a recent issue of Hand ?vIcNally & Co.’s 
Atlas. When there are no pul)lished data, the latitude 
and longitude, as shown by the station’s location in this 
atlas, are used. Altitude is determined by running a line 


of levels from the nearest “bench mark.” The height of 
the barometer cistern is taken as the official station alti- 
tude above sea level. The methods of determining true 
meridian are fully described in Bart II, section 2. As 
soon as the cardinal points are established, white posts 
are placed around the outer portion of the kite field, 
exactly north, northeast, east, etc., of the reel house, in 
order that wind direction, both at the surface and in the 
free air, may be accurately determined. 

The main building is of frame construction, one and 
one-half stories high, and is used for office quarters, 
carpenter shop, and kite storage. It is 26 feet wide by 
48 long and approximately 24^ feet from the ground to 
the peak of the roof. The dimensions of the office and 
computing room are 25 by 14 feet; of the carpenter shop, 
25 by 12 feet; and of the kite storage room, 25 by 20 
feet — all inside measure. An attic provides additional 
room for the storage of kites, extra kite sticks, and mis- 
cellaneous supplies and equipment. Full specifications 
and sketches are on file at the Central Office of the Weather 
Bureau. Figure 2 gives a front view of one of these 
buildings. 

2. KITE REEL HOUSE. 

It is necessary to have a small building of special 
design and construction in order to obtain the best 
results in kite flying. This building consists essentially 
of two parts — a turntable, by means of which the door- 
way may be presented to any desired direction, and a 
superstructure sufficiently large to accommodate the 
kite reel and accessory apparatus. The whole is 
mounted on a circular concrete wall 20 inches thick and 
30 inches deep, inclosing a space 10 feet 8 inches in 
diameter. This inner space is excavated to a depth of 
2 feet below the top of the wall, thus providing ample 
room for adjusting the electric wiring from time to time 
as it becomes twisted due to the turning of the house, 
and for inspecting the “ground” connections, turntable, 
etc. The turntable consists of five curved pieces of 
heavy iron rail, on which turn the wheels that carry the 
weight of the building, the turning being readily accom- 
plished by means of an endless cable leading from the 
trucks to a suitable hand apparatus mounted inside the 
house. The wooden building itself is about 15 feet in 
diameter at the floor, tapering to 14 feet at the eaves. 
The floor is about 2 feet 9 inches above the ground; the 
eaves, 12 feet, and the [leak of the roof, 15 feet. At tln^ 
front of the building is a doorway about 8 feet in width 
and e.xtending from the floor to the eaves. This largo 
doorway is provided because, in addition to the reel and 
the theodolite which occupy a part of this space, it is 
necessary for the observers to pass in and out occasion- 
ally in order to launch or land kites, make observations 
of clouds, etc. A small window at the rear of the house 

7 


8 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


gives additional light and ventilation, and a trapdoor 
provides easy access to the space inclosed by the founda- 
tion wall. At northern stations it has been found 
advantageous to have about one-third to one-half of the 
reel house divided off by a wooden partition, this small 
room being heated by an oil stove during cold weather to 
lessen the discomfort of the observers on duty. 


sun’s rays. Additional protection is provided in this 
case by a sloping roof attached to the reel house and 
projecting about a foot beyond the limits of the instru- 
ment shelter. Generally speaking, this extra precaution 
is unnecessary, since there is usually a good breeze blow- 
ing, and therefore plenty of ventilation, while a kite 
flight is in progress. 



;pen f^ield 

Fio. 1. — Plot showing the position of buildings and kite hold at Ellendale Aeroiogical Station. 


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A wind vane is attached to the top of a vertical shaft 
extending through the peak of the roof, and at the lower 
*end of this shaft another arrow is fastened with the 
same orientation, thus making possible the determination 
of surface wind direction from inside the reel house. 
On the left side of the building, as one faces the doorway 
from the inside, a standard Weather Bureau instrument 
shelter is installed. This shelter, as is well known, has a 
double roof to prevent heating of the inside air by the 


Complete specifications and drawings for the con- 
struction of reel houses are on file at the Central Oi'fice of 
the Weather Bureau. A general view of one of these 
reel houses is shown in (igure .‘b 

:5. KI’l’E REEL AND MOTOR. 

The kite reel, noAV in general use at Weather Bureau 
aeroiogical stations, was originally designed by I’rof. C. 
F. Marvin and later modified by Dr. Win. K. Blair. 


Fig. 2.— Front view of office and kite .storage building at Broken Arrow Aerologieal Station. 




Fig. 3.— Close view of kite-reel bouse at Kllendale .terologicul Slation, 





Kic, <!.— Kiglit fiotit. viovv of kilo rool. 





i'lO:. 5. — l,i‘fl fniiil view of kilc ri-cl. 







Fig. 6.— View of rear of kite reel; also of variable-speed motor. 




INSTRUCTIONS FOR AFROLOOK^.AT. OBSERVERS. 


9 


Excopt for tho drutu, it is inado larpioly of cast iron and 
its weight is such as to render it stable under any pull that 
may bo o.xortod by the kites. Two views are shown in 
liguros 4 ajid 5. Tho most prominent features arc the 
solid base and substantial frame, the drum and the 
three small wheels which guide the wire from tho drum 
to tho kites. One of those wheels, at the front, is so 
mounted that it can accommodate itself to the direction 
which the wire assumes under the influence of the wind’s 
action on the kites. The other two wheels, at the top, 
are mounted on a distributor carriage which travels back 
and forth under the action of a cam, shown in the 
upper right-hand part of figure 5. Other details in this 
figure arc the hand brake and wheel and the operating 
gears. In figure 4 may be seen the foot brake and wheel 
(auxiliary to the hand brake), a Veeder counter, and a 
dynamometer for indicating amount of wire out and 
puU exerted by the kites, respectively. The drum, 
which is the result of numerous trials with different 
types, consists of three pieces — the barrel and two 
spiders. The former is made of cast semi-steel and the 
latter of cast irqn. The spiders merely center the 
barrel on the shaft and rotate it, but carry none of the 
accumulated strain to which the drum is subjected by 
the piling up of the successive strands of wire. On the 
same shaft with the drum are mounted the two brake 
wheels and two driven gears, already referred to. The 
latter, shown in figure 5, are of different diameter, the 
larger being for slower speeds. The gears engaging 
these arc always in mesh, and power is applied to either 
of them by means of a double-throw friction clutch at 
the rear of the reel within easy reach of the operator. 

Complete specifications and drawings for construction 
of kite reels are on file at tho Central Cflicc of the 
Weather Bureau. 

The Tcile reel motor . — Power is furnished by an electric 
motor, so designed as to run at any speed between 
about 400 and 1,800 revolutions per minute, and for 
any pull up to that equivalent to about 5 horsepower. 
Such motors can be obtained for either direct or alter- 
nating current. Power is transmitted by means of 
chain and sprockets. One of these motors (for direct 
current, in this case) is shown in figure 0. Speed is 
regulated by means of tho shaft leading from the motor to 
a position within easy reach of the operator. As already 
stated, the speed can be still further regulated by the use of 
one or the oth(*r of the two driven gears shown in /iguro 5. 

Protection against lifihtnirKi (contributed in part by 
Mr. R. N. Covert, Meteorologist). — Both in and out of 
the Weather Bureau service tlu; Hying of kites has been 
attended by danger from lightning to tlu! persons engaged 
in the wmrk, and witli the continued growdh of tho Aero- 
logical Section of tho service it becomes more and more 
necessary to use every precaution to avoid possible injuries. 
In addition, damage to propei'ty should be minimized. 

It is well known that even the wet string used in 
flying common kites will occasionally permit a con- 
siderable discharge to earth during a thunderstorm. 


Blit when steel wire is employed to hold a box kite, the 
metal provides a better conducting path for the lightning. 
A direct discharge from clouds to earth will quickly melt or 
vaporize tho wire, but tho wire will have directed tho dis- 
charge, tho air along tho path becoming a good conduct- 
ing medium by reason of its becoming ionized. There 
is also occasionally a considerable inductive discharge. 

From the foregoing, there evidently must be some 
reliable moans for conducting dangerous discharges to 
earth as well as for completely insulating the reel when it is 
desired to measure the atmospheric electric potential. 
This has been accomplished according to the following plan. 

The kite reel is insulated from the floor by being 
mounted on blocks of fiber, as indicated in figure 6, and 
the sprocket which is driven by the chain from the 
motor is composed for the most part of fiber. This 
insulation makes possible the measurement of elec- 



Fia. 7. — Method ofaUachingcoppcrcablolomain "ground” pipe. 


trie current on tho kite wire. Although such measure- 
ments have yielded little of scientific interest, they arc 
useful, especially in summer, as indicators of possible 
trouble from approaching thunderstorms, of tho exist- 
ence of which, however, there is no other evidence. 
Under such conditions disruptive discharges of consider- 
able intensity sometimes render advisable the shorten- 
ing of a flight which otherwise might have been continued 
until too late for completion before the arrival of a 
thunderstorm. Accordingly, Weather Bureau stations 
are furnished with electrostatic voKineters of the Braun 
typo for this purpose. A long switch, wliicli is opened 
during these measurements, at other times coimec-ts tlie 
reel with a Vc-if'ch stranded co|)pcr cable to a “ground” 
formed by driving a lO-foot length of ll-inch galvauiziid- 
iron pipe vertically into tho earth and fitting the u])per 
end to receive a connector, as shown in figure 7. 'khe 
attachment at the reel is formed as directly as possible. 


10 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


all sharp bends being avoided. As an added precaution, 
a copper cable is led from the reel to the trucks which 
carry the wheels, and the rail upon which the kite house 
turns is then grounded by making four connections 
through No. 6 copper wire to four 10-foot lengths of 
f-inch galvanized-iron pipes placed 90° apart just out- 
side the pei’iphery of the structure, as shown in figure 8. 

The foregoing description and the following instruc- 
tions should be supplemented by those given in Farm- 
ers’ Bulletin No. 842, which contains general information 
regarding lightning protection. 

Attention should, in particular, be given to the grounds 
to see that they are well made, and it should be known 
with certainty that the pipes are in contact with soil 
that is moist throughout the year. Furthermore, the 
iron-pipe grounds must be periodically inspected to learn 
to what extent corrosion is occurring, and the pipes 
replaced as often as needed. After the connections have 
been completed to the ground pipes, paint the upper 
ends of the pipes and the attached fittings with two 
coats of metallic paint. 



Fig. 8. — Method of attaching copper wire to “ground” pipes placed at stated intervals 
around the peripliory of the reel house. 


Following is a list of the material required for pro- 
tecting one reel house: 

12 feet ^-inch copper cable. 

2 ^-inch solderless connector.?. 

1 J by I inch galvanized machine bolt. 

1 U-inch galvanized malleable-iron cap. 

10 feet Ib'inch galvanized standard pipe. 

40 feet |-inch galvanized standard pipe. 

4 f-inch malleable-iron caps. 

8 I'inch, 12-24, round-head iron machine screws. 

8 iron washers for same. 

6 feet No. 6 copper wire. 

1 switch for breaking “ground.” 

In addition to the precautionary measures above out- 
lined, it has been found advisable for those engaged in 
the work to be provided with rubber gloves and boots 
during thunderstorms. Moreover, the utmost care should 
be taken in landing a secondary kite. 'Ihe splice wire 
should be taken off at the reel house and the kite then 
landed at as great a distance from the wire as jiossible; 
otherwise the observer might readily form a short circuit 
for the lightning from the kite wire to the earth. Dur- 


ing extreme conditions it is even advisable to clamp the 
brake securely and leave the reel house, with the kites 
still flying, until the passing of the storm. 

4. KITE WIRE. 

In meteorological kite flying, steel music wire, popu- 
larly Imown as "piano” wire, is generally used for the 
main line; it is far superior to any other material thus 
far tried for this purpose, because in it are combined the 
very desirable qualities of great and uniform strength in 
proportion to weight and bulk, and a smooth surface. 
This wire is manufactured in a large number of sizes 
varying between about 0.01 and 0.125 inch in diameter 
(Nos. 0 to 30, music-wire gage), and usually is sold in 
coils of various amounts and lengths, the smaller sizes, 
as a rule, being in longer pieces than the larger. For 
the main line, the longest pieces obtainable should be 
used in order to avoid the necessity of maldng numerous 
splices. Obviously, assuming adequate strength, the 
smaller the wire the better, for convenience in handling. 
The sizes between 0.028 and 0.044 inch in diameter are 
most frequently used in kite flying. The 0.028-inch size, 
used by the Weather Bureau during the early days of 
kite flying, is quite satisfactory for small kites and ascen- 
sions to moderate heights, although the tendency of small 



wire to kink is a disadvantage. When high flights with 
a number of kites are desired, larger sizes of wire become 
necessary, and the usual procedure at aerological stations 
of the Weather Bureau is to make up the main line of 
the following sizes: 0.032 inch, 500 meters (approxi- 
mately); 0.036 inch, 1,500 meters; 0.040 inch, 2,500 
meters; 0.044 inch, 10,000 meters, or 14,500 meters in 
all. The proportions vary somewhat, according to the 
average wind conditions. In the South, for example, 
more of the smaller sizes can be used than in the North. 
The tensile strengths of the sizes iTulicated are, respec- 
tively, about 300, 330, 420, and 480 pounds, and the 
maximum working strains 200, 250, 300, and 350 pounds. 

When wire is wound on the reel, the coil is placed on a 
spool; the end of the wire on the inside of the coil is 
attached to the drum or spliced to the outer end of the 
wire already on the drum, as may be necessary, and the 
entire coil is then wound on the drum, the reel being 
run by power ot' by hand, as pieferrcd. 

Splicinfi the wire requires considerable care. As the 
result of extended experience, it has been fouT\d (hat the 
best method is to twist the wires evenly about a common 
axis for a length of 5 or 6 feet, (hen turn the free ends 
closely around the main line for a length of about half 
an inch. These two processes arc accomplished very 





Fk:. U. — One method of reeling wire from the kite-reel ilrum to a snnller drum. 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


readily l^y moans of simple tools, as shown in lifijures 9 
and 10. The two wires to he spliced are held firmly by 
means of an ordinary machinist’s hand vise, having brass 
jaws to prevent cutting tho wire. This hand vise is not 
showm in the illustrations. The two wires are then 
placed in the shallow converging slots of the larger 
“twister,” figure 9; held in position, hut not clamped^ 
by the spring and set screw above the part containing 
the slots; and finally twisted uniformly, each about a 
common axis. The free ends are then wound closely 
around the main wire by means of the smaller “twister,” 
shown in figure 10, which scarcely needs explanation. 
Some difficulty is experienced in making an even splice 
of two wires of different sizes, and care must be exercised 
lest the smaller wire be the only one twisted. The 
process is aided if this smaller wire is held at a greater 
tension than the larger. It has not been found neces- 
sary or desirable to solder the splices, although that 
practice was followed during the earlier years of kite 
flying. The end of the wire to which the kite is to be 



Fia. 10.— Method of turniag end of loose wire around main wire by means of “small 

twister." 

fastened is passed through a swivel and secured to the 
main line by splicing in the same manner as for ordinary 
splices, except that a length of about 1^ feet is sufFicient. 

While the wire is being wound on the drum, machine 
oil should be poured over it from time to time, in order 
to prevent it from rusting. This should also he done 
occasionally after the wire has been used during rainy or 
snowy weather. Vigilance in tliis respect is well repaid 
in reducing the number of breakaways due to defective 
wire. Moreover, it is well to examine the splices from 
time to time and to renew them, if the main wire at the 
ends of the splices shows signs of wear. Such renewal 
can be effected during kite flights, but a preferable method 
is to wind the wire from the reel on a small drum, make 
the splice or splices, and then rewind on the reel. Figure 
11 shows one way of doing this. In winding the wire on 
the small drum, power is furnished, through chain and 
sprockets, by an automobile truck. As soon as all splices 
have been examined and, if necessary, renewed, the wire 
is rewound on tho drum of the kite reel, power in this 
case being furnished by the motor in tho usual way. 


1 1 

During this process it is well to wipe ofl' tlic old, dirty oil 
with a piece of waste, then pour new oil on the wire as 
it is being wound on tho drum. 

5. KITES AND KITE MAKING. 

In practical kite flying, as exemplified at the aerological 
stations of the Weather Bureau, the object is to attain as 
great a height as possible, without incurring serious risk 
to the kites or line. Obviously, the larger the size and 
number of kites used, the stronger — and consequently 
heavier — must the kite line be. Considerations of the 
effects of wind pressure and ease of handling restrict the 
diameter of steel wire that it is practicable to use for line 
to certain narrow limits of tensile strength. Limitations 
in the dimensions, etc., of the line must, therefore, be met 
by efficiency in kite performance. 

Of the qualities that an efficient kite should possess 
lightness, stability, and strength are the most important; 
but lightness must to some extent be sacrificed to realize 
the ideal practical kite. Of the many tj^^pes and patterns 
of kites that have been suggested or tried the Hargrave 
cellular kite or some modification of it (in the work of the 
Weather Bureau, the Marvin-Hargrave) remains the 
standard. In addition to its good flying qualities, it is 
perhaps better adapted to the tandem method of flying 
than is any other type of kite. 

The tandem method of flying and the design of kites 
and accessories best adapted to it were naturally devel- 
oped from experience and the knowledge of the atmos- 
phere obtained during early efforts to attain high altitudes 
by means of kites. Apart from practical reasons, the 
frequent stratified condition of the atmosphere as regards 
wind velocity and humidity imposes a limit upon the size 
of kites that should be used. It is not often that the 
wind is so uniform or increases so uniformly with altitude 
that a high flight can be safely made with one kite large 
enough to lift the necessary length of line. By distribut- 
ing the kites along the line, suitably to the prevailing 
wind and weather conditions, tho maximum lifting powei* 
of a given surface can be realized, without at any time 
exposing the whole of this surface to sudden changes in 
pressure of the wind. 

Abrupt changes in wind and weather with time or 
altitude usually afl'ect the lifting surface along only a 
portion of the line, the total increase of tension of the 
line from such causes depending largely on the area of 
lifting surface affected, and the methods for preventing 
excessive pull emhodied in the construction of the kites. 
In the Marvin-IIurgravc kite, excessive pull is prevented 
by its method of bridling, described in detail in a later 
paragraph. This feature of its construction is flexible, 
permitting a relatively greahu- margin of safety with 
increase in size of the kite. 

The ideal conditions under wdiich a high flight couhr be 
successfully made with one kite can not be foreseen with 
enough certainty to warrant the necessary equipment of 
suitable line or large kites, even if such equipment wore 


12 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


safe or practicable. There is, in addition, the fact that 
the tension indicated at the lower end of a line from which 
a single kite is flying is only one factor of the maximum 
tension on the line. Including the effects of wind pres- 
sure on the line, the maximum tension occurs where the 
kite is attached, and is equal to the tension indicated at 
the reel plus the weight of the vertical projection of the 
line. Under actual conditions, the tension to which the 
line is subject is a complex of the action of gravity, the 
pressure of the wind on the line, and the pull of the kite, 
and departs more from the indications at the reel, the 
higher and farther away the kite is flying.* Wlien the 
weight of the line is suspended from a number of kites at 
considerable intervals of distance, the difference between 
the maximum tension on the line and that indicated at 
the reel is practically negligible. 

Under the adopted method of tandem ffyhig, the range 
or variety in size of kites that it is advisable to build 
is established by the experience of the kite flier, the 
mechanical skill of the kite builder, and a knowledge of 
the tensile strength of the different sections of the line 
employed. It is unnecessary to build a kite much smaller 
than one which, under the most severe conditions, will 
exert a pull nearly equaling the tensile strength of the 
smallest diameter of line used. In the other extreme, 
the size of a kite should not go beyond that defined by 
caution in flying and limit in permissible fragility. One 
or two intermediate sizes in addition give a complement 
of kites that serves all purposes of every-day flying, and 
admits of easy standardization for manufacture. 

The Marvin-Hargrave Jcites now used are essentially of 
the same type and construction as those devised by Prof. 
Marvin,* and used at 17 stations during the Weather 
Bureau kite campaign of 1898. The only important 
modifications that have been introduced since that date 
are in the dimensions and in the adoption of the elastic 
bridle, experience having shown that a smaller and 
stronger size of kite is required for high winds, while for 
light winds a greater spread of sustaining or lifting sur- 
face is necessary. 

Three sizes of kites are most frequently used. They 
are illustrated in figure 12. They may he classed as 
high-wind kites, moderate-wind or standard Ivites, and 
light-wind kites. A fourth size, slightly larger than the 
standard but smaller than the light-wind kites, is some- 
times used. The details of construction for the different 

1 Monograph, “The Mechanics and Equilibriimi of Kites,” by Prof. C. P. Marvin, 
particularly pp. 64 to 70. (See Monthly Weather Review, April, 1897.) Thismono- 
graph was submitted in competition for, and was awarded, the Chanute prize olTcred in 
1896 by the Boston Aeronautical Society “for the best monograph on the kite, giving a 
full theory of its mochanies and stability, with quantitative computations appended.” 
It was written at a time when the mechajiics of the cellular kilo— the progenitor of the 
heavier-than-air machine — was being closely sludied. The stndcnl of the equilibrium 
of kites is referred to this monograph in its entirety for a full mathematical treatment of 
the subject. 

’ Concerning the history of the meteorological kites now u.scd in Iho United Stale.s,it 
maybe of interest to note that in the early days of kite flying at Blue Hill Observatory, 
Massachusetts, II. Helm Clayton made many improvements on the Hargrave box kite 
of 189.7. The most important modification was the use of longitndinalstieksconnecl ing 
the two cells at their outer corners, thereby greatly increasing the strength and stability 
of this kite. Prof. Marvin added the excellent folding feature, which jiot only makes it 
easy to ship kites, but also allow.s ready reassemblagc with unimiiaired strength. 


sizes arc precisely the same, the only differences being 
in the dimensions and proportions. As will be under- 
stood from the description and detail drawings which 
follow, this form of construction has certain advantages 
and disadvantages. One of the chief disadvantages is 
its frailty. Collision with the ground or other object 
almost invariably causes a bad smash of the kite; like- 
wise, when the sails become water-logged the shrinkage 
of the cloth combined with the pressure of the wind is 
frequently powerful enough to crush the framework of 
the kite. On the other hand, broken sticks are easily 
and quickly replaced and the kite itself is conveniently 
collapsed for shipment. This is a very important point, 
since occasionally the kites have to be returned from 
the surrounding country. 

As is well known, the kite consists of two cells joined 
together by longitudinal strips or sticks of straight- 
grained spruce. The front cell has a middle plane, and 
in this respect it differs from the original Hargrave pat- 
tern. The details which follow refer to what is known 
as the “standard kite.” This size, modeled after the 
pattern used in 1898, has been found to be the most 
suitable for a 7vide range of wind velocity and weather 
conditions. When properly built it will fly well in 
winds of from 12 to 30 miles an hour (5 to 13 meters per 
second) near the ground, and 70 miles an hour (31 meters 
per second) when 2 or 3 miles high. Its extreme dimen- 
sions are as follows: 

Ft. In. c.m. 


Length or distance fore and aft G 201 

Width or distance between the outside vortical surfaces... 6 4^ 194 
Height or distance from top to bottom of cell 2 8^ 83 


The area of sustaining or lifting surface is 63.8 square 
feet (5.9 square meters), and of steering or neutral sur- 
face 21.7 square feet (2 square meters). The kite weighs 
about 9 pounds (4.1 kilos). 

The material required in the construction of thestajidard- 
size Tcite includes: 

(a) Forty-three sticks of the following dimensions: 

L f 6y J inch by 7 feet 6 indies. Center bridle stick; square edges. 

1> I by I inch ))y G feet 10 inches. Lack center: square edges. 

4. I by inch by 6 feet 10 inches. Corners; square edges. 

I i>y A inch by G feet GJ inches. Horizontal front and back edges 
of kite; rounded edges. 

12, I by -j^ inch by 2 feet 7^ inches. Horizontal sides; rounded edges. 
Sj f by A inch by 2 feet 7-J inches. Horizontal intermediates, bracing 
horizontal front and back edges of kite; rounded edges. 

6, I by A iach by 3 feet 2 inches. Horizontal centers, bracing hori- 
zontal sides; rounded edges. 

3, g inch by A bich by 2 feet. Vertical center; rounded edges. 

(h) The sticks ai’c made of straight-grained spruce. 
All horizontal sticks slionld have their edges rounded, so 
that the end resistance of tlie kites to the wind will lie 
as small as po.ssibln. Fourteen yards of Lonsdale cam- 
bric* 26 inches wide are used for the sails; some coarse 
waxed linen thread for lasliing angles to sticks; 192 feet, 
of No. 1 I piano wire, diameter 0.t)24 inch, for guys. 

(c) Forty-eight metal angles of the pattern shown 
in detail in ligure 18 form the principal joints, 1 to 21, 



WWM 


l« 

1 

1 

40 1 




]'iG. 12.— Different sizes of box kites used at aerological stations. 





# 

' 1 \ 

■nnSSI 


u, 




Fni. 20. — Fosilioii and iiudii(»d of atlaelimenl (d iiu*le()rogni|)h in a kite. 







INSTRUCTIONS FOR AFROI.OOICAI. OBSERVERS. 


13 


figure 10; 34 metal angles of another pattern, shown 
in figure 19, are used for all intermediate joints, 
excepting at h'. d', n, p, y, and w, which arc simply 


Figure 13 is an elevation of the front or bridle face of 
the kite — i. e., the lower surface when flying. The 
opposite face — i. e., the upper or rear surface of the 



lashed with waxed thread. The isometric iletail, figure kite — is the sajiie except as to the size and length of 

18, shows how these joints arc fastened. These the bridle stick. Figure 14 is a sectional elevation 

metal angles are made especially for the Weather showing the central or bridle truss, and figure 15 is an 

Bureau. elevation of one of the two side trusses. The fine diago- 


14 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 


nal lines in figures 13, 14, 15, and 16 show the system of 
wire bracing necessary to preserve the form and rigidity 
of the framework. This bracing is all done with very 
fine piano wire secured to the metal angles, as shown in 
figure 18, for the vertical cross bracing. In the hori- 
zontal and long vertical bracing the wire is looped ovef 


Lonsdale cambric,^ 2 feet 2 inches wide and 18 feet 4 
inches long, and are double hemmed one-half inch on 
each edge and each end. A strong cord should be 
passed through this hem to lessen the danger of tearing. 
The sails are stretched around the kite frame and lashed 
to the horizontal and vertical sticks with waxed thread 



the small bolt head in the metal angles before the bolt 
is tightened up. All metal angles are lashed to the 
sticks with well waxed linen thread. 

After the frame is put together and securely braced, 
care being taken that all angles are true and square, the 
kite is ready for the sails, ddiese are made from white 


A middle sail is placed in the center of the top section, 
extending from MV to QZ (see fig. 16). This sail should 

s Tho rear coll and somotiraos botli colls arc covered wiUi a black fabric known t o tlio 
trade as “mercerized” silk or French porcaline, “batiste,” etc. It has the property of 
shedding water to a much greater extent than cambric. For thot reason kites covered 
with it are preferred during fog. Mo.st kites are made with a white front cell and a 
black roar coll, tho contrasting colors being very desirable for visibility. 


INSTRUCTIONS FOR AKROLOGl(L\L OBSERVERS. 


15 


bo exactly 2 foot wide and G foot inches long after this bridle is attached another stout cord in the form of 
being hemmed, as described for the main sails, and a double loop about 18 inches long, having at its end a 
should be lashed to the sticks in a similar manner. strong l)rass ring. This cord extends as shown and is 



stick at point 11, and to this is attached a cloth-bound making bridles is manufactured especially for the 
elastic bridle, formed as shown. To the outer end of Weather Bureau. It consists of thin strips of rubber 


10 


INSTKUCTIONS FOR AEROLOGICAL OBSERVERS. 


about one-quarter of an inch wide tightly bound in a 
cloth cover, in the form of a small braided rope about 
five-eighths inch in diameter. On account of the elas- 
ticity of the rubber this arrangement protects the kite 
and wire from injury by sudden gusts or strong winds 
by allowing the kite to fly at a smaller angle of incidence, 
thus diminishing the pull. 

The head kite, which carries the meteorograph, is fas- 
tened directly to the line by means of the brass ring in 
the outer end of its bridle. The secondary kites are 
flown by means of cords about 125 feet long. These 
cords are attached to the main line in the following 
manner: A piece of No. 9 soft iron wire about 6 feet 
long is bent so that a small open ring about an inch in 


In the lighl-wiruL Icite the change in proportions from 
the standard is the reverse of that of the hig h -wind 
kite — i. e., the width is . increased in proportion to the 
length fore and aft. The dimensions are increased over 
all, giving this kite a lifting surface of. 93 square feet 
(8.6 square meters) and a weight of 11^ pounds (5.2 
kilos). It will fly in a slightly lighter wind than the 
standard, but its chief advantage is characteristic of all 
large kites — it will lift more line after it has ascended 
into a current stronger than necessary to lift itself. Its 
ability to fly in a lighter wind is due to the fact that it is 
lighter for the same lifting sm-face than the other kites. 
The frailty of this kite is partly compensated for by the 
fact that it is used only when surface winds are light to 



"lonq unde>' head 

Fig.W 


Brass rm^ for ai'^chin^ 
kde tvire 


Enlarged Meka! damps 


diameter is formed near one end. About an inch of the 
wire at each end is then bent at right angles, thus: 

I 0 — I. This piece of iron wire is wrapped tightly 

about the main line, and the cord holding the secondary 
kite is tied into the ring. 

The method of attaching the meteorograph to the 
head kite is shown in figure 20. 

In the Imjh-wind Idle the proportions and dimensions 
of the standard size are preserved, except that the 
width is made 11 inches less, thus reducing the width 
of the lifting surfaces and relatively increasing the area 
of neutral surface. It has a lifting surface of 54.6 sejuaro 
feet (5.1 square meters). Tliis kite has been successfully 
flown in an 80 mile per hour (36 m. p. s.) wind at an 
altitude of 1 mile (1,600 meters) above the ground. 


moderate, and the chances of the kite’s striking the 
ground consequently small. It is not used when wind 
velocities aloft exceeding 30 miles per hour (13 m. p. s.l 
are expected, for, while it has been foiuul to possess fairly 
good flying qualities in a 50 mile per hour (22 m. p. s.) 
wind at an altitude of 2 miles (3,200 metprs) smaller 
kites can be more easily handled and more advanta- 
geously used in the stronger winds. 

With a given pattern of kite, any increase in size, 
without a more than corresponding increase in weight, 
will bo at the sacrifice of rigidity of the framework. In 
the three sizes of kites described and illustrateil, and other 
sizes and shapes that have been experimented with in the 
past, there is only a small range in the minimum wiiul 
velocities in which they will rise from the ground. The 


INSTUlTCrnONS FOli AEROL()(JU!AL OHSEKVKRS. 


17 


excess of wind velocity above that necessary to fly the 
unburdened kite will bo available to lift a weight I’oughly 
in proportion to its lifting surface. 

The lifting capacity of a Hargrave kite is partly a 
function of its shape. For a given area of horizontal sail 
surface, the lifting capacity can be increased by making 
it wider relative to its length, since, in all kites the pres- 
sure of the wind is greatest near the front edge of the sails.* 
By increasing the length and depth relative to the width, 
the lifting capacity is lessened, but the stability of the kite 
improved. However, not much latitude is permitted 
the kite builder in either direction, as on the one hand a 
kite proportionally too wide will fly badly in any consid- 
erable wind, while a kite too long and deep will not have 
lifting power enough, in relation to the pull it is capable 
of, to justify its use. 

A certain sturdiness of framework is necessary in all 
kites, not only to minimize breakage from inevitable 
collisions with the ground, but also to maintain good 
flying properties in strong wind. The wire ties in the 
Marvin-Hargrave kite serve to hold the framework 
symmetrical as a whole, and add little to the weight. A 
kite so braced will not collapse in any wind in which it is 
advisable to fly. An exception occurs when the sails 
become wet, but under such circumstances frailty is 
sometimes an advantage, by preventing a possible break- 
age of the line. However, unless the sticks are given an 
adequate thickness, distortion or deformation of the frame 
and sail surfaces, and consequent erratic action of the 
kite, will result during strong winds. 

The stability of any kite is observed to increase with 
height above the ground, especially the first few hundred 
meters. For a considerable distance above the ground, 
the ability of a kite to withstand strong wind increases at a 
rate greater than can be accounted for by the diminishing 
density of the air. There seems little doubt that this 
can be explained entirely by turbulence, gustiness, eddies, 
and convectional currents, the effects of which on the kite 
are strongest near the ground. 

fi. METEOROGRAPH. 

It is apparent that an instrument adapted to the pur- 
pose of exploring the atmosphere by means of kites 
must be accurate, light, durable, and compact. The 
meteorograph designed by Prof. Marvin is very satisfac- 
tory in all these respects, and is simply an ingenious 
combination of well-known devices used in recording 
pressure, temperature, relative humidity, and wind 
velocity. As shown in figures 21, 22, and 23, the essen- 
tials of this instrument are a light, rigid tube and frame- 
work, firmly united, which serve as supports for the 
several recording devices and provide satisfactory e.x- 
posure for the sensitive elements. The anemometer, 
temperature element and hygrograph hairs are mounted 
inside this tube, and the pressure element is secured to 
the frame in which, also, is clamped the clock drum. 
The four pen arms are mounted on the outside of the tube 

‘ For footnote see page 12. 


and connected with the sensitive elements by means of a 
simple linkage, adjustable in order that the range of 
movement of the pens or their position on the record 
sheet (as explained in detail hereinafter) may be changed 
if necessary. With the exception of the clock movement, 
the bearings and links (which are of German silver) and 
the brass screws and nuts, the instrument is constructed 
of aluminum, and weighs but 2.5 pounds. A removable 
cover protects the mechanisms from injury when the 
instrument is in use. The screening tube is insulated 
from this cover by strips of bakelite. 

During a flight the meteorograph is secured inside the 
kite in such a position that the wind passes freely through 
the tube containing the temperature element and hygro- 
graph hairs. In this way a very satisfactory exposure is 
obtained; the ventilation is good, since the wind is 
always strong enough to support the kite, and insulation 
is further minimized or eliminated by the shading of the 
instrument by the kite. A brief description of each ele- 
ment and its characteristics will, perhaps, lead to a 
clearer understanding of the workings of the meteoro- 
graph. Reference should be made to figures 21, 22, and 
23 for illustration of the parts described. 

Pressure element . — Two nickel-plated, steel vacuum 
cells, such as are used in aneroid barographs, are pre- 
vented from collapsing by a strong steel spring. Any 
change in the air pressure causes an expansion or con- 
traction of the cells and a consequent movement of the 
free end of the spring (the other end being rigid), and 
this causes the connecting arm to be raised or lowered the 
same amount. This vertical movement caused by the 
expansion or contraction of the cells is changed to a hori- 
zontal movement of the pen resting on the record sheet, 
and at the same time considerably magnified by a simple 
right-angle lever connection. Since the instrument is often 
carried to an altitude of 5 kilometers or more, and since 
this distance is recorded in a space of about 5 centimeters 
on the record sheet, it is very important that the pen 
record accurately. The usual difficulties mot with in the 
aneroid cell are overcome as far as possible. The link 
is so simple and direct that there is little chance for lost 
motion or friction. These must be watched for, however. 
The combination of two colls gives twice the power of 
one to the spring and conseciuently the pen arm, and also 
makes the movement “stifl’er;” that is, it takes a greater 
jar or vibration to move the pen from its proper position 
at any time, and any possible friction in the bearings or 
connections has a smaller effect on the movement of the 
pen arm. Since, then, a change in the pressure expands 
or contracts the cells, the movement of which is multiplied 
by the link and recorded by the pen, it is simply a matter 
of determining how much any certain change in pressure 
moves the pen on the sheet. The methods of deter- 
mining this and similar values will bo described in 
section 7. 

All aneroid cells are affected by changes in temperature, 
an increase in temperature lessening the resistance of the 
spring and vice versa. To “compensate” for this a little 
air is allowed to remain in the cell and then after testing 


46329—21 2 


18 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


at the factory a bimetallic strip is introduced in the link 
to “compensate” the element with still greater refine- 
ment. The compensation, however, is never perfect; 
hence, it is necessary to determine just what effect any 
temperature change will have on the pressure element 
and make allowance for it. 

The pressure pen is usually placed in the middle of the 
record sheet. Sometimes, however, it may be advisable 
to change this position, for example, if an unusually 
high flight is expected, and this is easily done by simply 
turning the adjusting screw on the pressure element. 
This screw should always press against the frame, as 
otherwise the element will be loose. 

If we wish the pen to move farther than it does for any 
definite change in pressure, we can loosen the small set 
screw in the link and push this lever arm in toward the 


center; then the same motion of the element and its con- 
necting arm will cause a larger angular motion of the 
adjusted arm and the pen. In this way the amount of 
motion of the pen arm compared to the actual change 
in the element, called the “scale value,” can be made 
practically anything desired. 

Temperature element . — The temperature element is 
made of “thermostatic” metal which consists of closely 
united strips of “invar” and bronze 25 mm. wide, bent 
into nearly a complete circle. A small steel spring inserted 
inside the element and attached to its ends increases its 
elasticity. The invar does not expand or contract with 
a rise or fall in temperature, but the bronze does, thereby 
causing the element to open or close; this motion is 
transmitted directly to the pen arm by means of a simple 
link. Since the coefficient of expansion of bronze is a 


linear function of the temperature, it is found that the 
movement of the pen arm is in direct ratio to the tem- 
perature change; in other words, the scale value for any 
one instrument is a constant. The exposure of the ele- 
ment being excellent, there is no appreciable sluggishness 
on account of lack of ventilation, and therefore the ele- 
ment adjusts itself quickly to any change in temperature. 

The temperature pen is set near the top of the sheet, 
allowance being made for any increase in temperature 
with altitude. The position of the pen on the sheet may 
be changed by loosening the brass set screw and then 
turning the pinion situated just above this set screw and 
between two other small brass screws. One end of the 
temperature element is rigidly connected to a rack which 
is moved by this pinion. The other end of the element 
ids connected to the lever arm and link. Moving the pen 


in this manner does not change the scale value, which is 
altered in exactly the same manner as is that of the 
pressure element. 

In some of the newer meteorographs the link has been 
so constructed that the scale value may be changed in 
any of several ways. The principle of the mechanism, 
however, is the same in every case. Moving the connect- 
ing point toward the center of rotation causes that point 
to move through a greater angle with the same change of 
the element, and vice versa. 

Humidity element. — Free-air relative humidities are 
usually obtained by means of the hair hygrometer. 
Human hair has the property of lengthening or contract- 
ing about 2 per cent, when subjected to extremes of 
moisture. The hairs arc mounted longitudinally in the 
horizontal screening tube. (See fig. 24.) The individual 



Fig. 24.— Horizontal screening tube in kite meteorograph, showing method of mounting hairs of hygrometer (a, fi.Ked post; 6, pivoted arm; c, pen arm; d, spring tor holding 

hairs at constant tension). 







CQ O 




Fig 21.— :^ont view of Marvin kite meteorograph (.4, screening tube; £, pinion: C, set screw; 72, adjusting screws (humidity): F, anemometer liead; 7’, bakelite collar; «. conned ing arms and 
J^ver. H, adjusting nuts on pen arms; I, adjusting screw (pressure): J, pen lifter; A”, knurled nut; L, pens: bukelite strip; N, lever; 0, connecting arm; P. spring on huniiditv element 

Q, pivots of pressure cell; R, aneroid cells; S, frame; T, steel spring; U, pen arms; V, clock cylinder; W, thumb .screw; A', record sheet). 





Rear view of Marvin kite meteorograjih ( T, steel spring; tension sj)ring). 




Fig. 23,— End view of Marvin kite meteorograph (S, frame; V', cylinder: Z, anemometer). 




INSTRUCTIONS FOR AEROLOOICAL OBSERVI^RS. 


19 


hairs are mounted separately instead of in a bundle. 
This method makes the element more quickly respon- 
sive to any change in humidity. The hairs are connected 
as directly as possible with the recording pen, thus re- 
ducing to a minimum the possibility of lost motion or 
friction in the bearings. Two sots of hairs are used — 
one running from an adjustable post at a to the pivoted 
arm at h, this arm also being connected with an adjust- 
able post; the other from the lower end of the arm at & 
to the pen arm at c. A small spring at d, or outside the 
tube on new instruments, keeps the hairs at constant 
tension. This tension should simply be sufficient to 
take up any slack in the hairs and to overcome any possi- 
ble friction in the movement of the pen arm. The dou- 
bhng of the strands of hairs in this fashion is equivalent 
to extending the hairs for twice the distance of either 
strand alone and hence the movement of the pen arm is 
twice that of a single length. Before mounting, all of 
the hairs are subjected to the same conditions of tempera- 
ture and humidity and the same tension and are fastened 
firmly with shellac. It has been foimd that an element 
in which the hairs are thus mounted responds very quickly 
to changes in humidity, whereas, when the hairs are 
arranged in a btmdle they require a relatively long time 
to change from dry to wet conditions and especially 
from wet to dry. 

Any change in the relative humidity, then, changes 
the length of the hairs, and this change is communicated 
directly to the pen arm. The change, however, is not 
linear with respect to the humidity change. Thus it is 
found that twice the change in humidity does not cause 
the pen to move twice the distance that a unit change 
would cause it to move as was found in the case of the 
temperature element. For this reason a special scale 
has to be made up for each humidity element showing the 
movement of the pen arm for any definite change in 
humidity. 

The position of the humidity pen on the sheet may be 
easily changed. The two adjustable posts mentioned 
above are held in position by small thumbscrews on the 
outside of the screening tube and may bo moved either 
way by loosening the thumbscrews. This either increases 
or decreases the distance between the posts, the slack or 
tension being adjusted by the small spring connected to 
the axle of the pen arm. 

The post that is connected directly with the pen arm 
is threaded and the position of the small clamp nuts 
holding the hairs on this post may be changed by moving 
the clamp nuts up or down. In later instruments the 
adjustment is made by means of a set screw in a small 
cylindrical block which can be made to slide up or down 
the post. In either case a movement up or down causes 
a change in the scale value of the humidity element. 
Thus, when the device that holds the hairs is moved 
downward, the post moves through a greater angle than 
before for the same change in humidity. This greater 
angular motion of the pen arm causes the pen, of course, 


to move over a greater distance on the sheet. Thus by 
trial and adjustment the scale value can be made any- 
thing desired. The humidity pen should be placed in 
such a position that when the humidity is about 100 per 
cent the pen will be a little above the humidity space on 
the record sheet. 

Wind element . — The velocity of the wind is recorded 
by a small anemometer fan placed in the forward end 
(that facing the wind) of the screening tube. In appear- 
ance it closely resembles a diminutive electric fan, 
except that the pitch of the blades is much greater. 
The wind passing through the screening tube causes 
the windmill to rotate; this rotation is transmitted 
through worm gearing to a cam against which bears a 
lever secured to the pivot of the recording pen; when 
the cam comes to the proper position the lever is sud- 
denly pulled down and the pen makes a mark on the 
record sheet. It then retmns slowly to its former posi- 
tion. The scale value of this element is changed only 
by changing the pitch of the blades on the fan. The 
entire anemometer fan and its immediate connections, 
called the “anemometer head,” may be removed by 
unscrewing the three little brass screws in the collar 
running around the tube. This should be done only 
when absolutely necessary, as, for example, when it is 
desired to test the instrument in a small bell jar, for 
damage is easily done when replacing this head. The 
pen may be shifted forcibly when necessary to change 
its position on the sheet. 

The record sheet used is the same for all instruments. 
The wide space at the top side of the sheet is for the 
wind record. The temperature pen should record be- 
tween this space and the center of the sheet. The space 
for pressure runs from near this center line to the begin- 
ning of the space occupied by the humidity record. 
Here the lines are double spaced, for the record of hu- 
midity is not as accurate as are those of the pressure and 
temperature elements. Under extreme conditions it 
should bo possible for the pens to record outside their 
ordinary limits. Thus at an altitude of about 7 kilo- 
meters the pressure pen could record on the humidity 
space and the temperature pen on the pressure space 
and there would probably be no interference. 

The cloch cylinder may bo removed from the frame by 
loosening the thumbscrews on each end of the axis. 
Inside the cylinder is a specially made clock. The axis 
of the cylinder is one of the arbors of the clock and, 
when it is clamped in the frame at one end, the clock 
and cylinder rotate around it once in eight hours. The 
other end, the one with the largo knurled thumbscrew, 
is used for winding the clock and rests lightly on the 
frame. The clock is wound by turning this large knurled 
nut, holding the cylinder at the same time. The paper 
on which the record is to be made is properly trimmed 
and placed on the cylinder, the latter being, of course, 
removed from the frame while winding the clock and 
attacliing the paper. The record sheet is held in place 
by a brass strip which presses down upon the sheet and 


20 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


fastens in the side of the cylinder. The outer end of the 
sheet is always placed beneath the clip so as to give the 
greatest possible length of record before the pens have to 
pass over the clip. 

A pen lifter is provided by which, when the instru- 
ment is in the case or otherwise, the pens may be raised 
from the sheet. The lifter should always be worked by 
the lever inside the screening tube. 

The case or cover . — The instrument fits snugly into a 
light aluminum case in such a way that no part of the 
instrument except the inside of the screening tube and 
the anemometer head is exposed to the weather. Two 
bakelite strips insulate the tube from the case. A piece 
of mica in the case allows the action of the pens, whether 
they are inking properly, etc., to be seen while the instru- 
ment is still in the case. The case is fastened into the 
kite as explained in section 8. 

7. CALIBRATION OF METEOROGRAPHS. 

Before beginning any tests on an instrument it should 
be carefully examined to see that it is in good working 
condition. The cylinder should be removed from the 
frame and the clock wound. A record sheet should be 
trimmed along the line above the wind space and on the 
center line of the three close lines below the humidity 
space. The sheet is then placed on the cylinder so that 
the wind space is near the large knurled nut used to 
wind the clock. Where the ends of the sheet overlap 
the lines should be made to coincide and the paper 
should fit snugly against the front (wind) side of the 
cylinder. The brass strip is then put in place and the 
cylinder set in the frame in such a way that the pens are 
directly above the brass strip. The knurled nut at the 
right is tightened securely, but with the fingers only. 
The larger knurled nut is simply screwed up, not tight- 
ened. 

For convenience in testing these instruments a stand 
is made of two parallel strips of wood with ridges pro- 
vided for the lower part of the frame. This stand holds 
the instrument in the proper position and allows the 
cylinder to move freely. 

The pens are filled with the special ink provided and 
the adjusting nuts on the pen arms screwed down until 
the pens press lightly against the paper. The pressure 
should be sufficient to hold the pen against the sheet when 
the instrument is tilted about 20° from the vertical. The 
pens should be made to ink properly. It is sometimes 
necessary to draw a thin slip of paper between the points 
of the pens in order to start the liquid flowing through 
them. With new pens it may he necessary to smooth 
the points a very little to prevent their catching in the 
paper. The pressure pen should then he run down to the 
center of the humidity space and hack, this being done 
by turning the adjusting screw resting against the 
frame. If there is any mechanical obstruction to this 
motion it should be removed. If the difliculty can not 
be easily remedied the instrument should he returned to 


the instrument maker. No attempt should be made to 
repair the instrument. This applies to any adjustments, 
other than very simple ones, which may be found neces- 
sary. When repaired by other than an expert instru- 
ment maker the instrument suffers. While running the 
pen down and back it should be noticed whether it marks 
all the way or whether it rises from the sheet part of the 
way. (This may be due to a twisting of the frame and 
if serious the instrument should be returned for repairs.) 
The pen should then be forced two or three spaces to 
either side of its position of rest and allowed to return by 
itself. When the instrument is tapped lightly the pen 
should return to within at least two or three tenths of a 
space to its original position. If it does not do this 
there is something wrong. It may be lost motion or 
friction in the connecting link or perhaps the pressure of 
the pen against the sheet is too great. The latter may 
be tested by loosening the pen arm a bit and allowing 
the pen to rise slightly from the sheet. If it still fails to 
return the trouble is evidently elsewhere. The con- 
nections should be examined for tightness or looseness 
and altered, if necessary. The trouble may possibly be 
due to the fact that the adjusting screw is not resting 
tightly against the frame. If, after these and other 
trials that may suggest themselves, the pen does not 
return properly it is probably due to a weak or defective 
element which should be replaced by a new one. 

The temperature element should then be tested in 
about the same way, making sure that the pen can go as 
far as the wind and pressure spaces. The pen is moved 
by loosening the brass set screw and turning the pinion 
above it as described previously. The set screw should 
be tightened again, of course. The humidity pen is 
tested similarly by moving either of the adjusting posts. 
If this pen does not return when slightly displaced and 
jarred it may he due to the tension of the little spring 
on the pen-arm axle being too small or too great. Too 
great a tension will tend to cause a lag in the element. 

If the instrument is working properly to this point it 
is ready for the individual tests. These wall be described 
separately and in detail; first, however, a brief descrip- 
tion of the special apparatus necessary in testing each 
element will be given. 

Pressure test . — For this test an ordinary bell jar large 
enough to hold the instrument, preferably without remov- 
ing the anemometer head, an exhaust pump of the Geryk 
or other good type, a U-tul)o manometer, with attached 
thermometer, or other means of accurately measuring 
the pressure within the jar, together with the necessary 
connections, etc., are needed. Two pressure, tests are 
necessary — a preliminary one for the purpose of adjust- 
ing the range of the pen, and an inteTisive one to deter- 
mine scale values. The instrument is placed upon the 
wooden stand and the pressuie pen low(',i-ed against the 
sheet. The time should be notc'd. (vSee 'I'able I for 
entries referred to.) The instrument and stand are 
placed under the bell jar, and the pump is Iheu started 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


21 


for the preliminary test. The pressure should ho lowered 
gradually until the pen has run down to the top of the 
humidity space, and should then be about the minimum 
anticipated in any flight. If it is not, then the jar should 
bo slowly refilled, the instrument removed, and the con- 
necting link changed. In ordinary kite work the highest 
altitude often reached is about 5 kilometers, at which 
height the pressure is about 400 mm. Therefore the pen 
should be at the bottom of the pressure space at about 
this pressure. In a record flight the pen could go still 
lower, of course, since the humidity pen would doubtless 
be out of the way. Suppose, for example, that we run 
the pen down to the top of the humidity space and find 
the left arm of the manometer to read 260 and the right 
arm 275. The sum of these is 535 which, subtracted 
from the average pressure 760, gives 225 mm. as the 
pressure at that point. The pen has evidently moved 
over too small a distance for the indicated change ; there- 
fore the little connecting lever should be pushed in toward 
the axis of rotation so that the pen arm will move through 
a greater angle for the same change in pressure. Having 
adjusted the connecting lever until the desired range is 
reached, the intensive test follows. With the instru- 
ment still under the bell jar the clock is allowed to run 
until the pressure pen makes a straight or steady line. 
Then the air is pumped out until the pen has gone down 
about five spaces. The instrument is allowed to stay 
under this pressure until a straight line has been traced. 
The instrument should be jarred slightly a minute or so 
after the pump is stopped. When the steady line has 
been made, the pressure, as recorded by the arms of the 
manometer, and the temperature are read and entered 
and the pump started again. When the pen has gone 
down about five lines more the pump is again stopped 
for a similar period. These steps are repeated until the 
pen is about at the center of the humidity space. It is 
then allowed to return at about the same successive 
steps, the air being let into the jar by opening the stop- 
cock or by some other convenient method. The times 
of the beginnings and endings of each of these stops may 
be noted in the proper column if desired. When the air 
in the jar is again at atmospheric pressure, the pen is 
given suflicient time to return to its original level. It 
should be jarred several times if necessary. If the pres- 
sure in the room has not changed during the test the pen 
should return to very approximately its original level 
in five minutes or so. A complete test usually occupies 
about one hour and a half or two hours. Since the 
instrument, when in the kite, is .seldom or never subjected 
to changes as rapid as these, and since it is always under 
more or less vibration which tends to adjust the pens, it 
seems reasonable to assume that, if the element is work- 
ing properly and the pen returns properly under these 
conditions, it is working all right and that it will work 
satisfactorily when in actual use. When this result is 
attained it is hardly necessary to simulate the actual 
conditions of flight by taking a longer time, etc., for the 


tests. If, however, the pen does not return to within at 
least several tenths of a space of its original level (pro- 
viding the pressure has not changed) the element and 
its connections should again be examined and the ele- 
ment replaced if necessary. 

In performing these tests it is always desirable to 
notice the general behavior of the elements. Thus the 
pen should move smoothly and should move every time 
the pump exhausts air, etc. If there is a leak in the 
connections or bell jar, as indicated by the manometer, 
this leak should be shown by the trace. A leak is rather 
an advantage if it is not too great, for a small leak in- 
dicated by the trace shows that the pen and element are 
working properly and smoothly and that the element is 
responsive to very small changes in pressure. 

The above test is repeated at least once, since a single 
test is not sufficient to give accurate values for making 
up the necessary tables. The method of working up 
these tests to give the tables will be treated later on. 
Having obtained two or three pressure tests which are 
apparently satisfactory the temperature test is then 
made. 

Temperatvre test . — For testing the temperature element 
there will be needed a warm and a cold room, box, or 
other receptacle in which the ventilation, produced by 
an electric fan or otherwise, is good. If a box is used it 
should have a glass window, so that a thermometer placed 
inside the box may be read from outside. In cold 
weather the instrument may be placed indoors and out- 
doors alternately. In warm weather it may be possible 
to secure a low enough temperature by placing the 
instrument in a tight box containing chopped ice mixed 
with salt. Other means of securing still lower tempera- 
tures are very convenient but not necessary. To secure 
the proper ventilation an electric fan is usually placed 
in the box or other compartment in such a way that the 
air current caused by it blows through the screening 
tube. An ordinary mercurial thermometer is suspended 
or placed in such a position that the bulb is exposed to 
the same current of air as the temperature element and 
can be read through the glass window. 

In this test both the temperature and the pressure 
pens are allowed to record, for we wish to know the effect 
of temperature change on the pressure element as well 
as on the temperature element. The general method is 
the same as that followed in the pressure test. The 
instrument is set up before an electric fan and allowed to 
run for about five minutes or until straight linos are 
traced by the pens. The thermometer is then read and 
the instrument subjected to a temperature differing from 
the first by 25° to 30° C., if possible. It is placed in front 
of a fan in this compartment and allowed to run until a 
straight line is made at this new temperature. The 
temperature is then read again, this time through the 
window. After one or two such changes the number of 
lines which the pen has moved over should be compared 
with the temperature change as indicated by the ther- 


22 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


mometers. The recorded change in ordinate divided 
into the change in temperature gives the scale value, 
and if this is not approximately that desired the connect- 
ing link should be adjusted so as to give the desired value. 
In aerological work a factor between 0.9 and 1.0 is sought; 
that is, one space on the sheet should correspond to a 
temperature change between 0°.9 C and 1°.0 C. There 
are several reasons for this limitation of the scale value. 
It is evident that the farther the pen moves the easier it 
will be to read more accurately any definite temperature 
change. On the other hand, the distance that the pen 
can move is limited by the width of the record sheet; 
for, if it goes beyond its proper space, it is likely to inter- 
fere with the pressure trace and both records will be lost 
or useless. Hence, it is necessary to ascertain the extreme 
temperatures that are apt to be met with and then adjust 
the pen or connecting link in such a way that either 
extreme will be recorded, the lower usually being re- 
corded about the middle of the sheet and the upper near 
the wind space. It has been found that within the 
limiting range stated little difficulty is ever met with on 
account of interference, but any smaller scale value with 
a greater movement of the pen arm would be liable to 
cause such trouble. 

If the factor, as determined roughly from the first two 
or three changes, is approximately that desired the pro- 
cedure is repeated at least half a dozen times. This 
will give about 12 changes in all which, when averaged, 
should give a good mean value. The number of values 
necessary to give a good mean depends mainly on the 
consistency of the values; and if this is good, 15 or 20 
values seem to be sufficient. Two series of the above tests 
should therefore give a satisfactory scale value. 

Humidity test . — Some kind of a humidity chest or box 
is necessary for this test. Any box which is nearly air- 
tight and provided with a glass window and containing 
a ventilating fan will be found satisfactory. The tem- 
perature box, if such was used, may be made to serve 
this purpose also. The inside of this box should be 
lined or otherwise covered with blotting or absorbing 
paper which should be saturated with water. With the 
cover on tight and an electric fan going, the humidity 
inside will soon reach 90 per cent or higher. This gives 
a standard value of high humidity. A standard low 
humidity may often be reached in the open room. In 
winter when the temperature and humidity are low 
outside it is possible to get a very low humidity in a 
warm room. If such conditions obtain nothing further 
is needed. If not, then another box or a readjustment 
of the conditions in the same box is necessary. This 
time calcium chloride or sulphuric acid is placed in the 
box. The moisture present is soon absorbed by either of 
these and the humidity becomes very low. In addition 
to the box and electric fan some kind of a psychrometer 
is necessary. The ordinary psychrometer exposed to 
the electric fan will serve this purpose, but an Assmann 
ventilated psychrometer is more convenient. 


The humidity pen is made to record, and the instru- 
ment is placed in front of the fan in either the wet or 
dry compartment until a straight line is made. The 
psychrometer is then read and the instrument changed 
to the opposite condition of humidity and the procedure 
repeated. A trial determination of the scale value is 
made as in the temperature test and the scale value 
changed if desired. If the hairs are lowered the pen will, 
of course, move farther for the same change in humidity. 
As has been stated, the scale value is a variable depend- 
ing on the humidity. For this reason humidities ranging 
from about 10 per cent to nearly 100 per cent should be 
used to derive the proper changes in the scale value. 
By allowing the blotters to dry out partially the high 
humidity may be lowered and then by limiting the 
amount of the drying reagent the low humidity may be 
raised until all possible values are obtained. Wherever 
possible about fifty changes should be secured and 
these should be as evenly distributed as possible among 
the different possible percentages. The range of hu- 
nfidity for each test should not necessarily be large. A 
range of 20 per cent is sufficient to give a good test and 
is more desirable in some ways than a larger range. 

It is often possible, especially in preliminary tests, to 
make the humidity and temperature tests at the same 
time. The instrument is placed in a room or box where 
the temperature is high and the humidity low. It is 
then changed to a box containing soaked blotters and 
cracked ice with salt. The temperature range secured 
in this way may be 20 or more degrees and the humidity 
range 30 per cent or more. 

The temperature and humidity pens in these tests 
should be watched to see that they are responding prop- 
erly; that is, they should respond immediately to any 
change in the temperature or humidity. The humidity 
pen, however, usually takes a few minutes, or more some- 
times, to adjust itself. This does not happen very often 
in actual flight, for sudden changes are not the rule, and 
the vibration of the kite and instrument assists the pen 
in adjusting itself to any change. If the elements do not 
respond to the changes as quickly as desired they should 
be examined for friction, etc., or replaced if necessary. 

Wind test . — In this test an anemometer, for recording 
the number of miles of wind passing a certain point, and 
an anemoscope or wind vane are necessary. Ordinarily 
the station anemometer and vane are used for this 
purpose. 

The anemometer pen of the meteorograph is adjusted 
to touch the sheet and the time is noted. The meteoro- 
graph is then suspended from the anemoscope so that the 
ventilating tube carrying the anemometer always faces 
the wind. The time at which it is suspended should also 
1)0 noted. The wind should be somewhere near the aver- 
age met with in actual flights. At any rate it should not 
be an extremely light or high wind. The instrument is 
allowed to record for three or four hours or more and is 
then taken down, the time being noted. The number of 


INSTRUCTIONS FOR AFROLOGICAL OBSERVERS. 


23 


miles of wind that have passed the instrument is taken 
from the record of the station anemometer. Two or more 
of these tests should bo made. 

In all the foregoing tests if the scale values as deduced 
later on do not agree fairly well, further tests should be 
made. A disagreement or lack of consistency may indi- 
cate a poor element or a poor test. At any rate tabular 
values for standard use should not bo dependent on in- 
consistent tests. 

Time test. — This test may be made separately or the 
times noted on the other tests may be used. If it is de- 
sired to make a special test on the clock, all that is 
necessary is to allow any pen to record for about three 
or four hours and raise it at a noted time. At least 
two such tests should be made. 

Lengths of fen arms and centers of arcs. — For drawing 
the hour lines (see section 10) it is necessary to know the 
length of each pen arm and the point on the record sheet 
at which the pivot of the pen arm falls. To find these 
the length of each pen arm from the center of the pivoting 
point to the pen is measured. The inked pen is then 
run up and down the sheet making as large an arc as con- 
venient. The record sheet is then removed and with the 
length of the pen arm as a radius and each end of the arc 
as a center small arcs are drawn. The point of intersec- 
tion of these arcs is the center of the arc made by the pen 
arm. The position of each center is thus found and 
stated with reference to the number of lines that this 
center is below a certain point. Thus the temperature 
is measured from the top temperature line and the pres- 
sure from the middle line of the sheet, etc. All the in- 
struments now made by the Weather Bureau instrument 
shop have standard lengths of pen arms and centers of 
arcs so that it is not necessary to make these measure- 
ments on the new instruments. These measurements are 
as follows: Lengths: Wind, 86 mm.; temperature, 130 
mm.; pressure, 130 mm.; humidity, 99 ram. Center of 
arcs: Temperature, 25 lines below top temperature lino; 
pressure, 20 lines below top pressure line; humidity, 5 
lines below top humidity line; wind, center of wind space. 

Reduction of the tests: Pressure. — Table 1 shows a pres- 
sure test that has been made in accordance with the 
method outlined above. If reference is made to this 
table the following procedure w'ill he simple. The 
columns headed “ Notes,” “ Time,” “ Att. ther.,” " Manom- 
eter,” "Left,” and "Right” have already been filled in 
as described. The figures under the " Right ” and " Left ” 
columns arc added and the total is entered under "Sum.” 
Now, any change in the temperature of the mercury in 
the manometer will cause that mercury to expand or con- 
tract a certain amount, dependent on the height of the 
column and the coeflicient of expansion of mercury. For 
this reason all readings are reduced to zero degrees centi- 
grade. The glass also expands or contracts when heated 
or cooled, and so what wo really wish to determine is the 
diflerence between these two expansions. The easiest 
way to do this is to make up a table or graj)h showing this 


result. The values generally used are given in the Smith- 
sonian Meteorological Tables, 1918 edition. Table 47, but 
special graphs have been made up to facilitate these 
reductions. By reference to one of these graphs or to 
the original table the corrections indicated in Table 1, 
"Temp, cor.” column, will be found to apply. The argu- 
ments are the "sum” and the "attached thermometer.” 
Since the temperatures recorded are above zero, the 
mercury is occupying greater volume than it would at 
zero, and hence the corrections are subtracted. This gives 
the "corrected reading” in mm. In aerological work 
millibars are the units used, so mm. have to he converted 
to mb. by multiplying by 1.333224. This gives the 
corrected reading in mb. (For these corrected values; 
See Table 12, S. I. Metl. Tables, 1918 ed.) 

Table 1. 


(Washington, D. C., Dec. 24, 1919. Pressure tests Nos. 1 and 2. Meteorograph No. 25.] 


Notes. 

Time. 

Att. 

ther. 

Manometer. 

Sum. 

Temp. 

cor. 

Corrected 

reading. 

Ordi- 

nate. 

Scale 

value. 

Left. 

Right. 

mm. 

mb. 

Pens down 

9:043 

25.0 

14.5 

14.5 

29.0 

0.1 

28.9 

38.5 

3.4 

11.32 



25.0 

26.0 

26.5 

52.5 

.-2 

52.3 

69.7 

6.2 

11.24 



25.0 

37.0 

38.5 

75.5 

.3 

75.2 

100.3 

8.9 

11.27 



25.0 

49.5 

51.5 

101.0 

.4 

100.6 

134.1 

12.4 

10.81 



25.0 

65.0 

68.0 

133.0 

.5 

132.5 

176.7 

16.3 

10.84 



25.0 

83.0 

87.5 

170.5 

.7 

169.8 

226.4 

21.2 

10.68 



25.0 

109.0 

115.5 

234.5 

.9 

2-23.6 

298.1 

28.4 

10.50 



25.0 

131.5 

139.5 

271.0 

1.1 

269.9 

3.59. 8 

3.5. 4 

10. 16 



25.0 

159.6 

170.5 

330.0 

1.4 

328.6 

438.1 

• 1 2 

9.91 



24.5 

188.5 

201.5 

390.0 

1.6 

388.4 

517.8 

\53. 6 

9.64 

9.66 



24.5 

159.5 

170.0 

329.5 

1.3 

328.2 

437.6 

43.3 

10.11 



24.5 

121.0 

128.5 

249.5 

1.0 

248.5 

331.3 

31.8 

10.42 



24.5 

103.0 

108.5 

211.5 

.9 

210.6 

280.8 

26.8 

10. 48 



24.5 

81.5 

86.0 

167.5 

.7 

166.8 

222.4 

21.4 

10.39 



24.5 

70.0 

73.5 

143.5 

.6 

142.9 

190.5 

18.3 

10.41 



24.5 

54.0 

56.8 

110.8 

.4 

110.4 

147. 2 

14. 1 

10.44 



24.5 

42.0 

44.0 

86.0 

.4 

85.6 

114.1 

10.9 

10.47 



24.5 

29.5 

30.0 

.59.5 

.2 

59.3 

79.1 

7.4 

10. 69 



24.5 

19.4 

19.7 

39.1 

.2 

38.9 

51.9 

4.8 

10.81 



24.5 

17.6 

17.9 

35.5 

.1 

35.4 

47.2 

4.1 

11.51 



24.5 

34.8 

36.3 

71.1 

.3 

70.8 

94.4 

8.3 

11. .37 



24.5 

.53.0 

56.0 

109.0 

.4 

108.6 

144.8 

13.0 

11.14 



24.5 

73.5 

77.0 

150.5 

.6 

149.9 

199.8 

18.4 

10. 86 



24.5 

96.0 

101.0 

197.0 

.8 

196.2 

261.6 

24.7 

10.59 



24.5 

120.5 

127.5 

248.0 

1.0 

247. 0 

329.3 

31.9 

10. 32 



24.5 

147.0 

157.0 

304.0 

1.2 

302. 8 

403.7 

40.0 

10. 10 



24.5 

182.0 

195.5 

377.5 

1.5 

376.0 

501.3 

/51. 1 
\51.3 

9. 81 
9. 77 



24.5 

144.0 

154.0 

298.0 

1.2 

296.8 

395. 7 

39.2 

10,09 



24.5 

113.0 

119.5 

232.5 

.9 

231.6 

308.8 

29.9 

10. 33 



24.5 

98.0 

103.0 

201.0 

.8 

200.2 

266. 9 

26.1 

10.23 



24.5 

78.0 

82.5 

160.5 

.6 

159. 9 

213.2 

20.5 

10.40 



24.5 

50.2 

54.0 

10-1.2 

.4 

103.8 

138.4 

12.9 

10. 73 



24.5 

36.0 

37.1 

73.1 

.3 

72.8 

97.1 

9.2 

10. 55 



24.5 

18.0 

18.6 

36.6 

.1 

36.5 

48.7 

4.6 

10.59 

Pens up 

12:01p 











The next step is to determine the values of the ordi- 
nates. To do this wo find the number of spaces and 
tenths of a space or division that the pressure pen moved 
from its initial position when each stop was made. 
Thus in figure 25 the starting lino is 0.4 division above 
the lino next below it. Then on the first stop, just before 
the pump was started or just at the time the pressure 
reading was made, the trace shows that the pen moved 
3.4 divisions from the original point. The total number 
of whole divisions over which it has moved is 3. The 
lower point is exactly on the lino, and hence its frac- 
tional ordinate is zero, and the addition of these values 
gives the ordinate stated. Each successive stop is 
determined in the same way and entered as indicated in 
Table I under "ordinate.” From the lowest point. 


24 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


coming back, all the points are computed in exactly the 
same way but from the last position of the pen. This 
is about 0.3 of a division above the line below it, and 
on refilling the bell jar all points are computed from this 
point. By the side of each step in figure 25 is placed a 
numeral which is the number of tenths of a space that the 
point at which the pressure reading was taken is below 
the line above it. This facilitates reading the trace and 
assists the computers in checking the work. The starting 
and ending points are computed from the line below rather 


The scale values secured from other tests are plotted in 
the same way, either on the same or separate sheets, and 
straight lines drawn between successive points. The 
scale values at which each line passes through each fifth 
ordinate are set down and then the mean for each ordinate 
found. This method is shown in Table 6, which is self- 
explanatory. The mean values shown there are plotted 
in figure 26, as indicated by the large circles, and a mean 
curve drawn through them. In drawing the curves 
for the individual tests it seems best to make the lines 



Fig. 25.— Calibration or test of the dillercnt elements In a kite meteorograph. 


than from the line above, and hence the numerals placed 
there signify so many tenths above the line below. The 
ordinate values having been filled in, each value is then 
divided into its corrected reading in mb., and this gives 
the scale values shown. This procedure is followed for 
all the pressure tests. 

The scale values secured in the above manner now have 
to be plotted. Using coordinate paper and considering 
the scale values as abscissas and the divisions as ordinates, 
a graph is made similar to the one shown in figure 26. 


straight between the successive points, but the final 
curve should be smooth. 

Having determined the smooth curve showing the 
scale values of the element for various readings on the 
record sheet, the next stej) is to make up a table. 'Pho 
curve itself may be used for computifig values, but a 
table is more convenient. To use (he curve itself we 
take the ordinate reading and multiply it l)y (lie scale 
value for that ordinate as taken from (he smooth curve. 
The table is made up in the same way, taking eacli ordinat e 


INSTRUCTIONS FOR AEROLO(JI(^AL OBSERVERS. 


25 


and multiplying it by tho scale value for that ordinate. 
A straight interpolation is made for tho tenths of an 
ordinate. Thus, in tho mean curve drawn above, tho 
first ordinate gives tho scale value of 11.19 which has 
been entered in Table 2. The second ordinate gives 
he value of 11.16, etc. Each of these is then multiplied 



by its ordinate and the value set down as shown. This 
is done for all tho whole ordinate values that it is ex- 
pected will ever be used. These values for the whole 
ordinate values are then copied (to tenths only) in the 
first column of the table to be made up as shown in 
Table 3. As the points on the record sheets are read to 
tenths of a division, wo have to make interpolations 


for these intonnediato values. Very little error, or prac- 
tically none, is introduced by assuming that the mean 
curve is a straight line between successive whole ordinate 
values. Wo therefore divide tho dilferences (see Table 2) 
between any two whole ordinate values by 10 and add 
this figure successively to the scale value from the first 
to the second whole ordinate. Thus, in the example 
given, the difference in scale value between the fifth and 
sixth ordinate values is 10.87, which, divided by 10, 
gives 1.087. Starting with the value for the fifth ordi- 
nate, which is 55.25, and adding 1.087 successively to 
this value, we obtain the values shown in Table 3 for 
successive fractions of the fifth to sixth ordinate values. 
The difference between the sixth and seventh ordinate 
is then found and treated as in the preceding case. 
This is done for the whole table. Having read any 
ordinate on the record sheet, we simply have to refer to 
this table, and we have the change in millibars directly. 


Table 2. — Pressure differences (mb.) per sheet ordinates, from tests made 
Dec. 24, 1919, at Washington, D. C. 

[Meteorograph No. 25.] 


Ordinate. 


1 .. 

2 .. 

3.. 

4.. 

5.. 

6 .. 

7.. 

8 .. 
9.. 
10 
11 . 
12 . 

13 

14 

15 

16 

17 

18 
19 


22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 




Scale 

Ordinate X 

Differ- 


value. 

scale value. 

ences. 


11.19 

11.19 

11.13 


11.16 

22.32 

11.04 


11.12 

33.36 

11.00 


11.09 

44.36 

10.89 


11.05 

55.25 

10.87 


11.02 

66. 12 

10.74 


10. 98 

76.86 

10.84 


10.95 

87.60 

10.59 


10. 91 

98. 19 

10.61 


10.88 

108. 80 

10.55 


10.85 

119. 35 

10.37 


10. 81 

129. 72 

10. 42 


10.78 

140. 14 

10.26 


10.75 

150. 40 

10. 40 


10. 72 

160.80 

10.24 


10. 69 

171.04 

10.18 


10. 66 

181.22 

10.12 


10.63 

191.34 

10.06 


10.60 

201.40 

10.00 


10.57 

211.40 

10.15 


10.55 

221.55 

9.89 


10. 52 

231.44 

10.06 


10. .'iO 

241.50 

10. 02 


10. 48 

251. 52 

9.73 


10. 45 

261.25 

9.93 


10. 43 

271. 18 

9.89 


10.41 

281.07 

9.85 


10.39 

290.92 

9. 81 


10.37 

300.73 

9.77 


10.35 

310. 50 

9.73 


10.33 

320. 23 

9.69 


10.31 

329. 92 

9.32 


10.28 

339.24 

9.60 


10.26 

348.84 

9.56 


10. 24 

358.40 

9. 16 


10.21 

.367. 56 

9.47 


10.19 

377.03 

9.05 


10. 16 

386.08 

9.38 


10.14 

10.11 

395. 46 
404.40 

8.94 




A table as just described is made for each instrument. 
If there is any indication that the scale values of the 
element have changed, as might happen in a fall or 
blow, etc., another series of tests is made and the mean 
curve is compared with the one formerly used; if tho dif- 
ference is appreciable a new table is made uj). Tho in- 
struments should be tested about once in every three 
months, even if no appreciable change in the elements 
is otherwise shown, for in that length of time it is 
possible that the scale values might change, because of a 
chemical or elastic change in tho material of the element. 


26 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


Table 3. — Pressure differences (mb.) -per sheet ordinates, from tests oj 
Dec. 24, 1919, at Washington, D. C. 

[Meteorograph No. 25.] 


Ordinate. 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

0 


1.1 

2.2 

3.4 

4.5 

.5.6 

6.7 

7.8 

9.0 

10.1 

1 

11.2 

12.3 

13.4 

14.5 

15.6 

16.8 

17.9 

19.0 

20. 1 

21.2 

2 

22.3 

23.4 

24.5 

25. 6 

26.7 

27.8 

28.9 

30.0 

31.2 

32.3 

3 

33.4 

34.5 

35.6 

36.7 

37.8 

38.9 

40.0 

41.1 

42.2 

43.3 

4 

44.4 

45.4 

46.5 

47.6 

4,8.7 

49.8 

50.9 

52.0 

53.1 

54.2 


55.2 

56. 3 

57.4 

58.5 

59. 0 

60.7 

61.8 

62.9 

63.9 

65.0 

6 

66.1 

67.2 

68.3 

69.3 

70.4 

71.5 

72.6 

73.6 

74.7 

75.8 

7 

76.9 

77.9 

79.0 

80. 1 

81.2 

82.2 

83.3 

84.4 

85.5 

86.5 

8 

87.6 

88.7 

89.7 

90.8 

91.8 

92.9 

94.0 

95.0 

96.1 

97.1 

9 

98.2 

99.3 

100.3 

101.4 

102.4 

103.5 

104. 6 

105.6 

106.7 

107.7 

10 

108.8 

109.9 

110.9 

112.0 

113.0 

114.1 

115.1 

116.2 

117.2 

118.3 

11 

119.4 

120.4 

121.4 

122.5 

123. 5 

124.5 

125.6 

126.0 

127.6 

128.7 

12 

129.7 

130.8 

131.8 

132.8 

133. 9 

134.9 

136.0 

137.0 

138.1 

139.1 

13 

140.1 

141.2 

142.2 

143.2 

144.2 

145.3 

146.3 

147.3 

148.3 

149.4 

14 

150.4 

151.4 

152.5 

153.5 

154. 6 

155.6 

156. 6 

157.7 

158.7 

159.8 

15 

160.8 

161.8 

162.8 

163.9 

164.9 

165. 9 

166.9 

168.0 

169.0 

170.0 

16 

171.0 

172.1 

173.1 

174.1 

175.1 

176.1 

177.1 

178.2 

179.2 

180.2 

17 

181.2 

182.2 

183.2 

184.3 

185.3 

186.3 

187.3 

188.3 

189.3 

190.3 

18 

191.3 

192.3 

193.4 

194.4 

195. 4 

196.4 

197.4 

198.4 

199.4 

200.4 

19 

201.4 

202.4 

203.4 

204.4 

205.4 

206.4 

207.4 

208.4 

209.4 

210.4 

20 

211.4 

212.4 

213.4 

214.4 

215. 5 

216.5 

217.5 

218.5 

219.5 

220.5 

21 

221.6 

222.5 

223. 5 

224.5 

225. 5 

226.5 

227.5 

228.5 

229.5 

230.5 

22 

231.4 

232.4 

233.5 

234.5 

235. 5 

236.5 

237. 5 

238.5 

239.5 

240.5 

23 

241.5 

242.5 

243.5 

244.5 

245.5 

246.5 

247.5 

248.5 

249.5 

250. 5 

24 

251.5 

2,52. 5 

253.5 

254.4 

255. 4 

256.4 

257.4 

258.3 

259.3 

260.3 

25 

261.2 

262.2 

263.2 

264. 2 

265. 2 

266.2 

267.2 

268.2 

209.2 

270.2 

26 

271.2 

272.2 

273.2 

274. 1 

275.1 

276.1 

277.1 

278.1 

279.1 

280.1 

27 

281.1 

282.1 

283.0 

284.0 

285.0 

286. 0 

287.0 

288.0 

289.0 

289.9 

28 

290.9 

291.9 

292.9 

293. 9 

294.8 

295. 8 

296.8 

297.8 

298.8 

299.7 

29 

300.7 

301.7 

302.7 

303.7 

304.6 

305.6 

306.6 

307.6 

30.8. 5 

309.5 

30 

310.5 

311.5 

312.4 

31.3. 4 

314.4 

315.4 

310.3 

317.3 

318.3 

319.3 

31 

320.2 

321.2 

322.2 

323.1 

.324. 1 

325.1 

326.0 

327.0 

328.0 

329.0 

32 

329.9 

330.9 

331.8 

332.7 

333.6 

334.6 

335.5 

336.4 

337.4 

338.3 

33 

339.2 

340.2 

341.2 

342.1 

343.1 

344.0 

345.0 

346.0 

346.9 

347.9 

34 

348.8 

349.8 

350.8 

351.7 

352.7 

353. 6 

354.6 

355. 5 

356.5 

357.4 

35 

358.4 

359.3 

360.2 

361.1 

362.1 

363.0 

363.9 

364.8 

305.7 

366.6 

36 

367.6 

368.5 

369.5 

370.4 

371.3 

372.3 

373.3 

374.2 

375.1 

376.1 

37 

377.0 

377.9 

378.8 

379.7 

380.6 

381.6 

382.5 

383.4 

384.3 

385.2 

38 

386.1 

387.0 

388.0 

388.9 

389.8 

390.8 

391.7 

392.6 

393.6 

394.5 

39 

395.5 

396.4 

397.2 

398.1 

399.0 

399.9 

400.8 

401.7 

402.6 

403. 5 


The date on which the test was made, the number of the 
instrument, the station, etc., are indicated on the tabular 
sheet in order to associate the table with the exact instru- 
ment and tests and to avoid any possible error in getting 
the wrong table, etc. 

Temferature . — The reduction of the temperature test 
and the preparation of a table of values are comparatively 
easy matters. As indicated in the preliminary tests, the 
change in ordinate values of the pen is divided into the 
simultaneous change in temperature as shown by the 
mercurial thermometer. (Table 4.) This gives the 
scale value for that one change. The same is done for all 
the changes and then these are averaged. If there is any 
value which is seemingly too divergent from the others 
this should be checked carefully and judgment should be 
exercised in using such a value. If the number of indi- 
vidual tests on this element is small and the scale values 
found are not consistent further tests should be made. 
Having found a good scale value, any ordinate reading 
has only to be multiplied ])y this value to give the change 
in temperature for the ordinate change considered. This 
process may be followed each time a record is read, biit 
it seems more convenient to make up a table with this 
factor, giving all the values that will ordinarily be used. 

Temperature effect on pressure element . — The differences 
in temperature between successive steps in the tempera- 
ture test are divided by the corresponding changes in the 
ordinate values (read to tenths as usual) of the pressure 
pen. These values are shown in Table 4. The indi- 
vidual values are then averaged and the result expressed 


as the number of degrees’ change in temperature pro- 
ducing a change of 0.1 of a division in the pressure 
ordinate is used as the correction to be applied to the 
pressure ordinate values. 

Table 4. 

(Meteorograph No. 25. Tested Dec. 24, 1919, Washington, D. C.] 
TEMPERATURE TEST. 


Notes. 

Temp. 

Temp. 

difi. 

Ord.difi. 

Factor. 

Temp, effect on 
pressure. 




Pres. dill. 

Factor. 

Pens down 1:05 p 

23.0 







5. 5 

17.5 

19.0 

0.92 

6.8 

2.2 


22.8 

17.3 

18.8 

.92 

.9 

1.9 


5.0 

17.8 

19.0 

.94 

.9 

2.0 


24.1 

19. 1 

20.2 

.95 

.9 

2. 1 


5.0 

19. 1 

20. 1 

.95 

.9 

2.1 


24.2 

19.2 

20.7 

.93 

.8 

2.4 


5.7 

18.5 

20.7 

.89 

.6 

3.1 


24.2 

18.5 

20.6 

.90 

.8 

2.3 


5.6 

18.6 

20.0 

.93 

.8 

2.3 

Pens up 3:10 p 

23.8 

18.2 

19.6 

10)9)26 

.93 

.8 

10)2^ 

2.3 


HUMIDITY TEST. 


Notes. 

Dry 

bulb. 

Wet 

bulb. 

Humid- 

ity. 

Hum. 

difl. 

Ord. 

difl. 

Factor. 

Pens down 3:20 p 

27.2 

14.2 

21 

* 




22.6 

21.2 

89 

68 

7.2 

.94 


26.0 

12.8 

18 

71 

8.5 

.84 


22.0 

20.8 

90 

72 

8.2 

.88 


26.2 

12.8 

17 

73 

7.7 

.95 


21.8 

20.2 

87 

70 

7.5 

.93 

Pens up 4:48 p 

26.8 

13.2 

18 

69 

8.0 

.86 
6)5. 40 
.90 


TIME TESTS. 


Test. 

Pens 

down. 

Pens up. 

Time 

dill. 

mm. 

mm ./hr. 

Temperature 

1:05 

3:10 

125 

78.2 

37. 5 

Humidity 

3:20 

4:48 

88 

55.2 

37.6 

Pressure I 

9:04 

12:01 

177 

111.2 

37.7 

Wind 

9:24 

12:20 

176 

11.0 

37.5 


3776 


WIND TEST. 


Length of record, mm 107. 4 

Time in hours 2. 9 

N umber of marks 37 

Number of miles 91.7 


„ 107.4 X91.7X.447 

2.9X37X64 

Humidity . — The humidity scale value, as already 
stated, is a variable. It is greater at high than at low 
humidities. In reducing the tests the following pro- 
cedure is used: The humidity ordinate values are 
divided into the actual humidity change as shown by 
the psychrometer. (Table 4.) These individual values 
are then classified. First, the average humidities during 
the individual tests are found simply by adding the two 
humidities and dividing by two. Then all the scale 
values for average humidities falling between successive 
intervals of 10 per cent are tabulated. (Table 5.) Thus, 
the scale values having an average humidity from zero 
to 10 per cent are placed in the first column, etc. The 
headings are inclusive. In addition to the values taken 
from the tests of the instrument, values computed from 


INSTRUCTIONS FOR AEROLOOICAL OBSERVERS. 


27 


the beginnings and endings of flights are included. 
Thus, when the change in huniidity from the beginning 
to the end of a flight is considerable, this change can be 
divided by the ordinate change and a scale value 
obtained. Altogether about 50 or more values should 
be obtained in one or both of these ways and then 
classified as outlined. If the values are not entirely 
consistent and there is some doubt as to the quality of 
the test the values that are widely divergent should be 
omitted. These average values then, as found for each 
successive 10 per cent, are plotted as shown in figure 27, 
using the scale values as ordinates and the average 
humidities as abscissas. A smooth line is then drawn 
through or near the points. Usually a straight line 
fits the points about as well as any other, but if it is 
evident that the points follow a curved line such a line 
should be made. So far, the method has been similar 
to that used in making the pressure table. In place of 
the table, however, two scales are constructed. First, 
some arbitrary scale the divisions of which represent the 
readings on the record sheet (see fig. 28) is adopted as a 



Fio. 27.— Curve showing humidity scale values for different humidities. 

permanent scale. Another special scale (fig. 29) is then 
made up in such a way that, when placed alongside this 
first scale, the actual humidities corresponding to the 
ordinate values observed and indicated on the permanent 
scale will be shown. On this scale the value of 1 inch 
has been chosen arbitrarily to correspond to a change in 
humidity of 10 per cent. The scale is so graduated that 
one-tenth of an inch corresponds to a change in humidity 
of 1 per cent. The next step is to make the speciid scale 
for the instrument under consideration in sucli a way 
that the humidities shown on it when placed alongside 
the arbitrary scale will correspond with the tests. This 
is done in the following manner: From the smooth 
curve the values for each 5 per cent are read and entered 
in a table (Table 7) or on the same sheet. If a straight 
line has been drawn to represent the points it is evident 
that the differences between successive intervuds of 
5 per cent will be the same. Thus, in the illustration, the 
average scale value for 0 to 5 per cent is that shown at 
2.5 per cent, or 0.429, and that for 95 per cent to 100 per 
cent is 1.018. Dividing the difference between tliese two 
figures by the difference in humidities we have 


1.018— .429-^-97.5 — 2. 4 = . 0062, which, multiplied by 5, 
gives the constant differ- 


4 




I- 1 


• 3 


-5 


-5 


. 5 


2 


- 5 - 


A 

Fio. 28. — Arbitrary or 
measuring scale: 
Large divisions cor- 
respond to divisions 
on motoorograpti 
slioet. 


r75 


10 


w 

■95 

90 

85 

80 


once between successive 
intervals of 5 per cent. 

These values are entered 
in Table 7. Now 5 per 
cent on the permanent 
scale corresponds to one- 
half inch. It is evident 
that the distances on the 
special scales must be in- 
versely as their scale 
values. Thus, if the scale 
value is small it will take 
more divisions on the per- 
manent scale to cover that 
distance and cotisequently 
the distance between the 
humidities indicated o n 
the special scale must be 
greater. Since 5 per cent 
corresponds to one-half 
inch and since we have 
chosen the scale values for 
each 5 per cent, we divide 
the scale values into the 
metric equivalent of one- 
half inch, which is 12.7 
mm. This conversion is 
made since it is more con- 
venient to use these units 
in making the special 
.scale. The values thus 
found are the distances 
between the correspond- 
ing humidities on the spe- 
cial scale. These are then 
laid off on the special scale 
and the lines drawn as in 
figure 29. Thus, the dis- 
tance from 100 per cent to 
95 per cent is 12.5 mm. 
and from 95 to 90 is 12.9 
mm., etc. In order to 
avoid an accumulative er- 
ror in laying off these dis- 
tances it is better to aild 
the distances and lay off 
each successive distance 
from 100 per cent. These 
values for the successive 
intervals of 5 per cent are 
then evenly divided to 
give the intermediate per- 
centages. 

To use this scale, if the 
base line'for the humidity 
record is 56 per cent, for example, the zero of the per- 
manent scale is set on 56 per cent of the speciah^scale. 


70 


60 


50 


cr. 


40 


35 


30 


25 


20 


15 


10 


O 

Kia.2U. — Percentage 
scale, used with 
scale In figure 28, 
for determining 
values of relative 
humidity for any 
ordinate on me- 
teorograph shoot. 



28 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


Then, if the ordinate is 3.4 divisions below this point, we 
look down on the permanent scale to 3.4 and opposite 
it is the humidity for that ordinate. 

Table 5. — Humidity tests classified. 

[Meteorograph No. 25. Tested Dec. 24, 1919, Washington, D. C.] 


Per cent. 



0-10 

11-20 

21-30 

31-40 

41-50 

51-60 

61-70 

71-80 

81-90 

91-100 



0.60 

0.62 

0. 74 

0.85 

0.94 

0. 87 

0.85 

1.12 

1.11 



.42 

.50 

.64 

.49 

.84 

.76 

.92 

1.10 

.94 




.45 

.59 

.71 

.88 

.75 

.88 

1.04 

.98 




.77 

.79 

.60 

.95 

.66 

.95 

.85 





.55 

.63 

.76 

.93 

.69 

1.00 

.60 





.45 

.75 

.56 

.86 

.70 

.83 







.69 

.72 

.62 

.82 

.87 








.60 

.74 


















1.02 

3.34 

4.83 

5.29 

6.76 

5.25 

6.30 

4.71 

3.03 



2 

6 

7 

8 

8 

7 

7 

5 

3 

Mean 


.51 

.56 

.69 

.66 

.84 

.75 

.90 

.94 

1.01 


Table 6. — Values ofi mean 'pressure curve. 
[Meteorograph No. 25. Tested Dec. 24, 1919, Washington, D. C.] 


Ordinate. 

Scale values. 

No. 1 
ascent. 

No. 1 
descent. 

No. 2 
ascent. 

No. 2 
descent. 

Sums. 

Means. 

0 

11.42 

11.04 

11.64 

10.63 

44.73 

11.18 

5 

11.27 

10.80 

11.48 

10. 58 

44. 13 

11.03 

10 

11.12 

10. 53 

11.29 

10.59 

43.53 

10. 88 

15 

10.83 

10.43 

11.04 

10.64 

42 94 

10.74 

20 

10.72 

10.40 

10.79 

10.42 

42.33 

10.58 

25 

10.59 

10.45 

10.58 

10.26 

41.88 

10.47 

30 

10.42 

10.44 

10.39 

10.33 

41.58 

10.40 

35 

10.18 

10.34 

10.24 

10.20 

40.96 

10. 24 

40 

10.03 

10.20 

10. 10 

10.07 

40.40 

10. 10 

45 

9.89 

10.04 

9.98 

9.94 

39. 85 

9.96 

50 

9.80 

9.82 

9.85 

9.81 

39.28 

9.82 


Table 7. — Humidity scale values. 


Humidity. 


2.5. 

7.5. 

12.5. 

17.5. 

22.5. 

27.5. 

32.5. 

37.5. 

42.5. 

47.5. 

52.5. 

57.5. 

62.5 

67.5. 

72.5. 

77.5. 

82.5 

87.5. 

92.5. 

97.5 


Scale 

value. 

12.74- 

scale value. 

Accumu- 
lative sums. 

0.429 

29.6 

375. 4 

.460 

27.6 

345.8 

.491 

25.9 

318.2 

.522 

24.3 

292. 3 

.5.53 

23.0 

268.0 

.584 

21.7 

245. 0 

. 615 

20.7 

223.3 

.646 

19.7 

202.6 

.677 

18.8 

182.9 

.708 

17.9 

164. 1 

.739 

17.2 

146.2 

.770 

16.5 

129.0 

.801 

1,5.9 

112.5 

.832 

15.3 

96.6 

.863 

14.7 

81.3 

.894 

14.2 

66.6 

.925 

13.7 

52.4 

.956 

13.3 

38.7 

.987 

12.9 

25. 4 

1.018 

12.5 

12.5 


Time rate . — To get the time rate the length of the 
record in mm. is divided by the time in hours; this gives 
the time rate in mm. an hour. (Table 4.) A scale is 
then made up f^ir dividing time rate into minutes; for 
convenience it is usually made to cover a space of several 
hours. (See fig. 30.) The time rate will be found to vary 
somewhat, due to the influence of different temjieratures 
on the clock, and due allowance must be made for this. 

Wind . — In general the number of meters of wind 
necessary to make one mark of the velocity pen is found 


from the tests by dividing the number of meters of wind 
that have passed the instrument by the number of marks 
made by the pen in any test. The average of several 
tests is adopted as the true value. Then the time, in 
seconds, between any two marks, divided into this scale 
value gives the velocity in meters per second for the 
time included between the marks considered. 

In the work of the Aerological Division a modification 
of the above method is followed. The ordinary wind 
velocity scale of the Weather Bureau is used in the cus- 
tomary way and the velocity so obtained is multiplied 
by a constant or scale value. This scale value not only 
converts the miles per hour into meters per second (since 
miles per hour are given by the scale and meters per 
second is the unit desired) by multiplying by 0.447 (the 
conversion factor converting m. p. h. into m. p. s.), but 
it also takes into account the different time rates of the 
instruments, i. e., the triple register and the meteoro- 
graph, and the number of miles of wind necessary to 
make one mark. The time rate of the triple register for 
which this standard scale is made is 64 mm. per hour; 
consequently, any other time rate will change the scale 
value proportionally. Thus, for the time rate found 



above (37.6), the fraction, must be included in the 
formula shown below. On the triple register one mark of 
the anemometer pen means 1 mile, but this is not the case 
with the meteorograph. The number of miles per mark 
is found by dividing the number of miles of wind that 
have passed the instrument by the number of marks 
recorded. Thus, in the wind test illustrated there arc 
37 marks for 91.7 miles, one mark representing 2.48 
miles. The velocity indicated by the wind scale must 
then be multiplied by this value. Condensing the above 
factors into a simple equation we have the scale value 
equals 

length of record in mm. X miles of wind X 0.447 
time in hours X number of marks X 64 ’ 

„ , , length of record in lum.Xmi lcs of win dXO.418 8 

ca e va ue— ^ minutesxnumber of marks. 

Substituting the values found in the above test v\'e 
have the result shown in Table 4. The velocity at any 
desired point is then found by first placing ilio Weather 
Bureau wind scale in such a position tbat two of tlie lines 
on that scale coincide with the marks on either side of 
the point selected; the indicated velocity on this scale 
is then multijdicd by tlie scale value already determined 
from the formula above given. 


INSTRUCmONS FOR AEROL()(}ICAL OBSERVERS. 


29 


8. MAKING TIIK FLIGHTS. 

In order to make successful kite flights, it is important 
that the apparatus used in the work be maintained in 
first-class condition, and that all preparations bo made 
before the flights are started. All the men engaged in 
the work should become familiar with the handling of 
the kites, kite wire, tying of various knots, and, in fact, 
every phase of the work. The men should become 
familiar with the different sizes of kites used and the 
weather conditions in which the various sizes fly best. 
The behavior of the various kites should be noted from 
time to time, for it frequently happens that there are 
considerable differences in the flying qualities of kites 
that appear to be similar in every other respect. 

The kite that carries the meteorograph is known as 
the lead or the head kite; the other kites as secondary 
kites. It is best to use for lead kites only those that have 
been previously tried and found to be satisfactory. Of 
those used as secondary kites, the ones that fly best should 
be used nearest to the lead kite. 

Ordinarily, three men are necessary to make a kite 
flight, but when conditions are favorable, and three men 
are not available, it has been found that two can do the 
work satisfactorily; this is especially true when flights 
are being made during the night. \^Tien three men are 
available, one man operates the reel, another keeps the 
meteorological record and all notes of the flight, and the 
third launches and lands the kites, keeps the reel house 
clean and in order, and assists in other work. If but two 
men are available, one man operates the reel, and the 
other keeps the meteorological record. The other work 
is divided between them as best suited to the occasion. 

Carrying the Idles . — When a kite is brought out of the 
storage room into the open, care should be taken to 
handle it properly. The man handling the kite should 
consider the wind velocity and direction. If the wind 
is light, the kite can usually be handled best by taking a 
position inside, between the cells, and gras[)ing the 
bridle stick near the front cell with the right hand and 
one of the corner sticks with the left hand. If the wind 
is higher than (> or 7 m. p. s., the kite can be handled best 
by taking a position in front of the kite as it lies flat on 
the ground and grasping the front end of the bridle 
stick with the right hand and the front end of the upper 
rib with the left hand. The rear or black cell of the kite 
is then free to swing around, and care should be taken 
that it is not damaged by a sudden puff of wind blowing 
this end of the kite against some obstruction. How- 
ever, a kite held in this manner with its front end toward 
the wind can usually be handled without dilliculty. A 
kite should always be held so that the wind will pass 
through it, and in no case should it be held by any other 
portion than at, or very near, the junctions of the sticks. 
When a kite in the open is not needed immediately, it 
should be placed flat on the ground, in such a manner 
that the wind can pass freely through it, and held down 
by weights placed within the cells. 


Care of meteorograph . — The metciorological observer 
should examine the meteorograph and see that it is in 
working order before each flight, lie should wind the 
clock, ink the pens, and see that the pens mark. (See 
Part 1, sec. 7.) The pens should occasionally be 
thoroughly cleaned out, and always after a flight in 
clouds when the ink becomes watery through exposure 
to the damp air. The ink should flow a little more 
freely than is the case with surface recording instru- 
ments, since frequently at high altitudes the combined 
effect of strong wind and low humidity may dry the 
ink faster than it can flow to the points of the pens. 
The pens should rest lightly on the paper, but should 
still touch when the meteorograph is inclined at least 
30° away from the vertical; otherwise portions of the 
record may be lost, especially if the kite flies to one side. 
The shorter pen arms, having less flexibility and de- 
scribing arcs of smaller radii, should be given slightly 
more tension than the longer pen arms, in order to allow 
for the curved surface of the record sheet on the cylinder. 
Care should be taken that the movements of the pen 
arms are not obstructed, and that the anemometer is 
working properly. 

The meteorograph sheet should be trimmed along the 
red line at the top and enough cut from its lower edge 
to allow it to fit in between the flanges of the clock 
cylinder. The sheet should be placed carefully on the 
cylinder with its top edge fitted snugly against the 
flange of the cylinder, and so that the lines meet exactly. 
In clamping the cylinder in its place the thumbscrew 
on the right side should be made quite tight; otherwise 
the cylinder is likely to fall out of place during the flight 
and the record be lost. The exact time of putting the 
pens down should be recorded as the first note of the 
flight. A complete observation of the surface meteoro- 
logical conditions should be made at this time and re- 
corded. This observation should include the tempera- 
ture of the wet and dry bulb thermometers, the direction 
of the wind, and the amount, kind, and direction of 
clouds. If more than one kind of cloud is observed, the 
highest should be entered first. The meteorograph 
should be put into its case by grasping the framework 
between the clock cylinder and the ventilating tube 
with the left hand and lowering the meteorograph care- 
fully into the case, the case being held in tlie right hand. 
The cover of the case should be put on and fastened by 
the two side catches. Tlie meteorograph should then 
be put into the shelter. Before and after each flight, 
base-line values should l)e obtained, the instrument 
being allowed to record until the pressure, temperature, 
and humidity {)ens trace straight lines; for this, an 
interval of from 5 to 12 minutes is usually required, 
during which two or three readings of the psychrometor 
should be made. A reading of the station barometer 
should be made while the meteorograph is in the shelter 
both before and after each kite flight. 


30 


INSTEUCTIONS FOE AEEOLOGICAL OBSEEVEES. 


The meteorograph should be tied to the upper rib of 
the kite a little forward of the center, and it should be 
braced by four pieces of twine running from the junctions 
of the sticks at the four corners below. (See fig. 20.) 
Before releasing the kite the observer should see that 
the pens are recording and that the clock is running. 
All of the work done by the meteorological observer, in 
the way of preparing the meteorograph for the flight 
and recording the meteorological conditions prevailing 
at the time of the flight, should be checked by the man 
operating the reel. Both men should satisfy themselves 
that the meteorograph is working satisfactorily before 
the kite is released. 

Launching the kites . — In taking the kite out for launch- 
ing, care should be exercised that the wire is not allowed 
to become slack. The kite should be held by the bridle 
stick at the rear edge of the front cell with the right 
hand, and at the lower corner stick with the left hand, 
as in figure 31. The man holding the kite should walk 
out with it held up at an angle of about 45° with the 
horizon, keeping a good tension on the wii’e between him- 
self and the reel all of the time. When the head kite is 
to be launched in a moderate wind, it should be taken 
about 60 meters to the leeward of the reel house and re- 
leased, if possible, while the wind is fairly steady; in a light 
wind it should be taken out 100 meters or more and 
pulled up into the air by reeling in; if the wind is strong, 
the kite should be released while walking away from the 
reel and should be allowed to go out rapidly, in order 
to prevent its diving to the ground, or jerking so as 
to injure the record. 

headings called for on the data sheet should be made at 
the times of laimching and landing of kites, when kites 
enter or leave clouds, and whenever there is a decided 
change in weather conditions. Wind directions should 
be given to 16 points. The exact times at which read- 
ings of the theodolite are made should be noted, as 
these are used in checking the altitudes determined from 
the meteorograph record. It is not so essential to get 
other readings precisely at the times noted, e. g., when 
a secondary kite is launched or landed, the time entered 
should be the time at which the angle is read, the exact 
time of the launching or landing being relatively unim- 
portant. While reeling in the first one or two thousand 
meters of wire, several observations of angle of the head 
kite and the amount of wire out, with the usual other 
readings, except that of the voltmeter, should be made 
in order to have a record of surface conditions at the 
time the meteorograph is at its greatest altitude. When 
the head kite is within 1,000 meters of the reel, the speed 
of reeling in should be reduced in order that a good record 
of inversions and other conditions near the surface may 
be obtained. 

Notes should be kept of changes in the kind, amount, 
direction, and altitude of the clouds. Whenever a kite, 
either the head or a secondary, enters or leaves a cloud 
layer, its angular altitude and distance out should be 


noted, as changes in altitude with time are most interest- 
ing and important. However, when the cloud layer does 
not appear to change much in altitude or structure, only 
occasional notes of the entry of secondary kites into the 
cloud base are necessary. Enter notes on all miscella- 
neous phenomena, such as times of beginning and ending 
of rain, snow, etc., solar and lunar halos, rainbows, 
thunderstorms and tornadoes. In making notes on the 
surface record, and in stamping and trimming meteoro- 
graph sheets, it is desirable that the work be done in a 
uniform manner; that is, when several people are doing 
this work, they should all do it in the same way. 

Wlien a secondary kite is to be lavmched, it is attached 
to the main wire by a piece of No. 32 blocking cord, about 
30 meters long. The cord is secured to the main wire by 
a Dines clasp, which is a piece of No. 9, 10, or 11, gal- 
vanized-iron wire, this wire being about 1^ meters long 
with short right-angle bends at each end, and a loop in 
it about half a meter from one of the ends. This wire is 
wound around the main kite line, with the loop end up, 
and the blocking cord is tied in the loop. A supply of 
these wires and cords should be kept in the reel house. 
The kite should be taken out about 50 to 150 meters, 
depending on the strength of the wind. If the wind 
velocity is high, the kite should be let out rapidly after 
launching, at the same time watching for a chance to get 
it above the main line. The kites should be let out at 
such speed that they maintain fairly good angles, but if a 
kite catches on the main line, it should be let out as 
rapidly as possible; if it fails to release it should be reeled 
in, as many a flight is ruined by a kite caught on the wire. 
If a kite falls on the wire from above, the “reel” man 
should stop reeling out and, if necessary, reel in a short 
distance, in order to allow the wind to lift it. 

Landing the kites . — When a secondary kite is landed, it 
can usually be brought close to the reel, but in a gusty 
wind it is best to stop 30 or 40 meters out in order that 
the wire may respond to the unsteadiness of the wind. 
The head kite should be landed about 40 to 80 meters out. 
While it is being run down, the reel man should have the 
handle on the axle of the reel drum, in order to lot out or 
pull in quickly, according to sudden changes in the surface 
wind. The head kite should be handled as carefully as 
possible, as accidents to the head kite nearly always 
damage the record of the flight. It is generally advisable 
when landing a kite in a strong wind to pay out line to the 
kite at the same time the kite is being pulled down. On 
the other hand, when landing a kite in a very light wind, 
it is best to walk away from the kite as though to fly it, 
while pulling it down, as otherwise the more act of pulling 
the kite down is liable to cause it to fly almost overhead, 
and then suddenly “volplane” down to the ground. 

In the case of breakaways, or the kites coming down, 
or any other accidents, complete notes should bo made 
at the time on the record sheet by the meteorological 
observer. If the kite breaks away ho should note the 
time of the breakaway and make a comj)loto metooro- 



j.'io, ;jl.— I'ropcr melliocl of holding a kite prepnratory to launching it. 




■'l- 



INSTRUCTIONS FOR AKROLOCxICAL OBSERVERS. 


31 


loj^ical observation at this time. He should watcli the 
kite through the theodolite * as long as possible and 
record the angles of elevation and azimuth and the time 
at which the kite disappeared. The ollicial in charge 
and every man on the station should bo notified imme- 
diately of the accident, and every man on the station 
should exert all possible effort to protect all roads, in 
order to prevent persons and vehicles from running into 
the wire while it is lying on the ground, and every effort 
should be made to gather up the wire as soon as possible. 
At times of accidents it is important that everyone on 
the station act quickly and intelligently in an effort to 
gather up the wire in order that no damage be done 
by it. 

Kite wire . — ^As safe kite flying is so largely dependent 
on the condition of the steel piano wire used, the utmost 
vigilance should be observed to prevent injury to it and 
detect any evidence of weakness throughout its length. 
When it is necessary to put new wire on the reel or to 
make splices in the wire, it is important that this be done 
with the utmost care. The wire should never be held 
by anything but a brass or copper jawed vise. The ordi- 
nary steel pliers have rough jaws that make indentations 
in the wire and weaken it considerably, and should not 
be used to grasp the wire. Too much emphasis can not 
be laid on the importance of always keeping the wire 
taut. After being repeatedly wound on and unwound 
from the reel drum and over pulleys, and particularly 
if the wire has been run under tension over wheels of 
too small diameter, or has rubbed against some solid 
object, such as the side of the reel house, a fence post, 
or tree, internal strains are developed that will cause the 
wire to coil as soon as it is slackened. If, on again 
tightening, a single coil becomes a kink, a breakaway 
beyond the kink is inevitable. The tendency to coil 
varies inversely as the diameter of the wire, and it is 
therefore advisable to feel out the smaller sizes of wire 
frequently when reeling in or out. 

Opportunities for the wire to slacken sufficiently to 
coil are always present when flying in light winds, and 
when, under such conditions, it becomes necessary to 
reel in rapidly to assist in raising the kites the reel should 
always be slowed down gradually before coming to a 
stop, if conditions permit. Rapid reeling out in a light 
wind, especially when pronounced convection currents 
are present, will often cause coiling and probably kinking 
of the wire. With a wind barely strong enough to sus- 
tain the kites in the air and convection currents prevail- 
ing, a wave-like effect is often observed, the kites rising 
and falling in succession. Then, if wire is paid out 
rapidly to the rising kite, the wire between it and the 
falling kite immediately in advance will slacken and 
probably coil. 

Another common source of damage to the wire is 
faulty wrapping of the heavy branch wire used to attach 

* The theodolite used in kite work is of tlie same dosiKn and construction as tiiat 
uso'l for observing pilot balloons. It is described in detail in I’art II, section 2. 


secondary kites. Under the direction of an experienced 
man a novice should learn how to attach this wire with- 
out leaving permanent sharp bends in the piano wire. 
Occasionally this branch wire should be shifted a few 
meters ® from its usual position on the line. When, 
after landing a secondary kite, it is found that the cord 
is wrapped around the main line, care should bo taken 
not to pull the cord too hard in the attempt to unwrap 
it, as this causes an injurious twisting strain on the wire. 
In an emergency it is better to cut the cord than to try 
to unwTap it hurriedly. 

The wire should be kept clean and slightly oiled. In- 
crustations of ice or frost should be wiped off when reeling 
in, and the wire again wiped with a piece of oiled waste 
when reeling out in the next flight. This wiping of the 
wire should be frequent; it not only serves to prevent rust- 
ing, but also, prevents kinks from passing by unnoticed,. 
Few breakaways are caused by the pull exceeding the 
normal tensile strength of clean undamaged wire. Kinks, 
sharp bends, rust spots, or flaws in the splices cause the 
majority of accidents. 

Observation and experience . — After having acquired 
training in the practical details of kite flying, as outlined 
in the foregoing paragraphs, the beginner should supple- 
ment this knowledge as soon as possible by close obser- 
vation of weather conditions and kite fl.ying, and as 
diligent study of upper-air records as his opportunities 
and capabilities permit. 

It should be the aim of the kite flying force to obtain 
the highest possible flights consistent with safety under 
various weather conditions, to preserve the continuity 
of daily flights for as long periods as wind and weather 
permit, and to reduce breakaways and other accidents 
to a minimum. All the competency of the force derived 
from experience and study will be needed to bring about 
these desired results. 

Because of ever-changing weather conditions with 
which the kite flier has to contend, it is evident that, 
except in a general way, no sot of rules can take the place 
of experience that has been accpiired by close observation. 
Much of what follows has a general application, and 
while many of the assumed situations relating to weather 
conditions and kite flying should bo taken with the 
reservation that they apply more strictly to the Middle 
West, it is felt that a discussion of them will servo the 
useful purjioso of guiding the interested beginner into the 
proper channels of observation and study. On the whole, 
the experiences mot with in kite flying in dill’erent por- 
tions of the country are undoubtedly similar enough in 
many respects to justify some general rules or suggestions. 

While a profound knowledge of meteorology is not 
necessary to practical kite flying, it must bo admitted 
that the greatest justilication for upper-air investigations 
will come from those stations where the interest of the men 

* Ordinarily, the secondary kilos arc attacliod at more or lass rcKular intervals from 
tlie head kite — e. g., 500, 1,200, 2,000 motors, otc. Tims, tlioro is a possiliility of weak- 
ening tlio kite wire by ropeatod wrappings of tbo “splico” or galvanliod-iron wire at 
the same place. 


32 


INSTRUCTIONS FOR AEROLOGICAU OBSERVERS. 


is aroused in the results as well as in the performance of 
their work. To the interested observer, a day-to-day 
comparison of the upper-air records with the weather map 
offers an unlimited field for study. As ordinarily the 
aerological stations do not have available weather maps 
of current weather conditions, it is desirable that the ob- 
servers make a study of local weather conditions, chiefly 
the record from the barograph, the observations of 
clouds, the kite records, and the weather maps that are 
received, and correlate these with the view of ultimately 
being able to anticipate to some extent upper-air condi- 
tions from local indications alone. For example, it is 
well to follow the progress of the barograph from day to 
day, and thus try to grasp the sequence of highs and 
LOWS, and their approximate relation to the station. 
At many of the kite stations observations are made twice 
daily with pilot balloons. The one in the early morning 
is of great value in connection with kite flying, in that it 
gives an accurate measurement of wind conditions at 
various altitudes and thus assists materially in deter- 
mining the number and sizes of kites to be used. Ob- 
viously such observations are limited by the height of the 
lowest cloud stratum, but even then they give valuable 
information as to the wind speed at any height below 
that level. 

Accuracy of record and good judgment in obser- 
vation are essential to a logical interpretation of the kite 
records. Opportunities for observations leading to im- 
portant deductions in meteorology occur frequently in 
kite flying, apart from those that make a part of the 
routine record. Initiative and alertness in work and 
observation are therefore valuable assets in the held. 

Discrimination should be used in those instances in 
kite flying that permit latitude of opinion. An example 
is the case of determining the direction of the wind aloft. 
This should be ascertained not only by observing the ap- 
parent direction of the head kite from the observer and 
the other kites, but also by the position of the kite in the 
theodolite (assuming that the head kite flies straight) and 
by whatever horizontal movement it may have. The ob- 
server should familiarize himself with the appearance of 
the kite in the theodolite at close range, in order that he 
may, when necessary, associate an angular appearance of 
the kite in the theodolite with direction of the wind in 
which it is flying. When the kites make a large “swing” 
during flights, a careful comparison of the apparent di- 
rections aloft recorded when reeling out with the appar- 
ent directions at corresponding altitudes when reeling in, 
will, to a large extent, eliminate the possibility of error. 
As it is often diflicult to determine actual directions of 
the wind aloft at night and when the kites are obscured by 
clouds, experience should be directed toward observing 
the relation between the azimuth of the wire as it leaves 
the reel and the direction aloft. 

When to reel in . — The observer should memorize the 
values of the sines of angles commonly recorded with the 
theodolite, thereby enabling him to compute approxi- 


mate altitudes quickly when necessary, and to keep con- 
stantly in mind the relation between the altitude of the 
head kite and the amount of wire out. So long as the 
head kite maintains a fairly steep angular altitude, (say 
30° or more) it may be assumed that the pull is at its 
maximum and that, barring a change in the weather con- 
ditions, reeling in will not throw the kites much higher 
nor materially increase the pull. Such a flight may be 
considered a normal one, and the number of kites to use 
and the distance to reel out will be clearly indicated by 
the dynamometer. 

Ordinarily, the final reeling in should commence when 
the stationary pull shows indications of passing 200 
pounds. Also, more kites should not be launched after 
the dynamometer reads between about 160 and 200 
pounds, this also depending on the number of kites al- 
ready flying. A little computation will generally settle 
this point. For example, when the pull of two kites is 
150 pounds, another kite is likely to increase the pull to 
225 pounds; while a pull of 175 pounds, with seven 
kites, will probably not be increased to more than 200 
pounds by the addition of another kite. The same rea- 
soning should be used when estimating the probable re- 
sult of reeling in, or of an increase in wind. Given a 
certain pull, it is obvious that reeling in or an increase in 
wind will augment that pull in proportion to the number 
of kites used. The tensile strength of the different sizes 
of wire used should be kept in mind, and precautions 
taken to avoid, as far as possible, taxing any of the wire 
to much more than half its normal capacity. 

Number of Tcites to use . — Judgment in the matter of 
number of kites to use should also be influenced by the 
possibility of the kites ascending into a decidedly stronger 
wind aloft with further reeling out. The winds nor- 
mally increase with altitude, but occasionally this rise in 
velocity is much more rapid or abrupt than usual. Indi- 
cations of an abnormal increase in velocity with altitude 
will usually be apparent to the careful observer by the 
action of the dynamometer, the movement of whatever 
clouds may bo present, the results of the preceding pilot 
balloon observation, if such was made, and especially by 
the tendency of the head kite to maintain or even in- 
crease its angle when reeling out. 

As long as the kites maintain a good angular altitude, 
there should ordinarily bo but little difliculty in making 
an excellent (light without subjecting the wire, to exces- 
sive pull. If, however, there is much wire out with 
many kites and tlie angle is low, success and safety will 
necessitate a rather tedious ])rograin of work. Under 
such circumstances, reeling In might raise all or most of 
the kites to such higher altitudes ami stronger winds as 
to increase the pull to the danger point. It will then be 
advisable to sound the strength of the upper winds by 
occasionally reeling in a few hundred meters before 
putting on additional kites, meanwhile watching the 
iiead kite through the theodolite. If the trial reeling in 
is not successful in permanently raising the kites, a note 


INVSTEUCTIONS FOE AEEOLOGICAL OBSEEVEES. 


should 1)0 mado, mental or otherwise, of the depth of the 
light wind. Eventually the decision should bo mado 
whether to reel in all the kites and rearrange them with 
a view to greater lifting surface by using more or larger 
kites, or to continue the flight with the expectation of 
finally lifting them into sufficiently strong winds aloft. 

After an altitude of between 2,500 and 3,000 meters 
has been sounded without indications of strong wind it is 
probable that no wind of dangerous strength will be 
encountered to an indefinite height. When an altitude 
of about 3,000 meters has been reached, with only a 
mo{lerate pull and a good angle, experience has shown 
that still higher altitudes may generally be obtained by 
adding more kites and reeling out farther, without ma- 
terially increasing the pull. This may be explained by 
the tendency of light wind to extend to high altitudes, 
and the fact that actual increase of velocity with eleva- 
tion is to some extent offset by the diminishing air 
density. 

The circumstance of kites flying at a low angle is often 
associated with a stratified condition of the air, manifested 
by a brisk shallow wind, on top of which the kites seem 
to float as though on a liquid surface, apparently in a 
calm and all flying at about the same altitude. This 
condition may be met with in winds from any direction; 
and except in easterly winds (for reasons explained later) , 
requires the exercise of caution lest too many kites be 
launched and exposed to the danger of a rise into winds 
too strong for the wire. The danger is to some extent 
proportional to the proximity of the lower winds to a 
westerly direction, being at a minimum in easterly winds, 
and at a maximum in winds between northwest and south- 
west. When kites rise above such a calm stratum they 
will as a rule enter a wind from some westerly direction, 
and cause a pull at the reel that will be partially a resul- 
tant of the direction and amount of the pulls of the 
individual kites. 

Kites floating above a shallow wind, other than easterly^ 
can generally be reeled up into higher winds aloft after 
four or five kites have been launched on a few thousand 
meters of wire. With easterly winds, however, the 
change in direction is often so abrupt, and of such angular 
magnitude in comparatively short intervals of altitude, 
that re[)eate<l reeling in will be useless. In such a case 
the final ascent of the leading kites into stronger upper 
winds can oft(*n be accom])lished by exercising patience. 
When, after a few attempts, it becomes apparent that 
reeling in is futile, it will be necessary simply to await the 
automatic rising of the kites incident to tlie development 
of wind that sometimes attends or follows a pronounced 
change in direction with altitude. With easterly winds 
near the ground and westerly winds aloft, it has been 
observed that the kites will more often show a tendency 
to shift to the right than to the left as they rise above the 
lower strata. 'I'liis shifting is generally slow and will not 
result in raising the kites until the upper portion of the 
wire is approximately in line with the drift of the upper 
4C329— 21 ^3 


33 

winds. The total change in asiimuth from the surface 
wind to the direction of the highest kite may be as much 
as 200°. 

A stratification of the air, causing the kites to appar- 
ently “float,” is quite common, and is due most often to 
abrupt, though not necessarily large, changes in wind 
direction with altitude. Sometimes a stratum of com- 
paratively calm air intervenes between two winds hav- 
ing nearly the same direction, in which case it is probable 
that the stratification is related to abrupt changes in 
temperature and humidity. 

Veering of winds with altitude averages greater than 
backing, both in frequency and angle, and is chai-acteristic 
of approaching lows and retreating highs. Backing 
of winds, associated with retreating lows and ap- 
proaching lUGHs, is usually more gradual, and in the 
case of retreating lows, is sometimes preceded by veering 
in the lower levels. The amount of shifting in wind 
direction with altitude has an important bearing on the 
number and size of kites that can safely or advan- 
tageously be used. The accuracy with which this dis- 
position of the winds can be foreseen will depend largely 
on the ease with which observations of cloud direction 
and velocity are made. 

Easterly winds as a rule should occasion no anxiety to 
the observer from the standpoint of excessive pull, 
unless complicated by heavy rapidly moving clouds. 
This assurance of generally safe conditions in easterly 
winds may not, however, apply to other than interior 
sections of the country. In the Middle West it has been 
found that deep cast winds are nearly always light to 
some unknown limit, and that when strong easterly 
winds occur, they either diminish with altitude or are 
rather uniformly strong with altitude. In the latter 
case, the number of kites to use is easily apparent. The 
condition of light easterly winds surmounted by strong 
easterly winds is probably rare. While in the case of 
kites swinging from lower easterly winds to upper west- 
erlies a strong current from the latter direction may bo 
encountered, it is likely that the pull will not be excessive, 
owing to the more or less opposing pull of the kites. 

'Weather types — A few llights will convince the ob- 
server to what extent success in kite Hying is measured 
b}' ability to anticipate conditions in altitude and 
changes with time. Considerations of pressure rank 
first in making deductions of probable upper-air condi- 
tions and should b(! judged somewhat as follows: The 
state of the barometer, whether rising, falling, or station- 
ary, anti whether above or below normal; the duration 
and magnitude of the rise or fall; and the probable 
geographic distribution of the pressure. 

Changes in the surface wind are inclined to bo syn- 
chronous with changes in pressure and the velocities them- 
selves proportional to the pressure gradient. This I'ola- 
tion between the surface pressure and wind is not so 
simple when applied to velocities aloft. It will often bo 
found that surface winds alone fail as an inde.x to the 


34 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


probable velocities aloft and that they should be con- 
sidered in connection with the previous few hours’ 
pressure record. It will often be necessary to wait 
until the first kite has ascended a few hundred meters 
before coming to a final decision as to what conditions 
to expect. 

A pronounced condition that has been repeatedly 
found in the Middle West, and that probably occurs in 
some modified form over the greater portion of the 
country, is that which accompanies a period of rising 
pressure when the pressure is already high. During 
the period of rising pressure strong winds, often increas- 
ing with altitude, will usually be found, while the least 
indication of flattening out of the barograph trace seems 
to be followed by diminishing winds — near the ground 
first, and progressively later at higher altitudes. The 
height to which the strong winds extend varies according 
to the structure of the high and the intensity of the pre- 
ceding LOW. While, without the aid of current weather 
maps, it will not ordinarily be possible to estimate the 
intensity of the pi'essure gradients surrounding the 
station, a knowledge of these facts, together with what- 
ever telegraphic information is available, will be helpful. 
If a flight has been started while the pressiu’e is rising 
steadily, and the pull soon reaches the limit of safety, it 
will sometimes be found advantageous to apply the brake 
and wait, an hour or more if necessary, until the ex- 
pected stable pressure, with its attendant abatement of 
winds, makes further reeling out possible. The higher 
the pressure the more likelihood there is that it will soon 
reach its crest. Periods of rising pressure are often 
accompanied by stormy weather, more especially while 
the pressure remains low. The barograph and wind- 
register record should then be watched, as well as the 
weather, in order that the most opportune time for 
starting a flight may not pass by. Under these condi- 
tions the pressure will sometimes stop rising simul- 
taneously with, or soon after, the ending of precipitation 
and the wind become too light to launch a kite. 

After the pressure becomes high and stationary, the 
winds will be light to moderate to a considerable alti- 
tude, their average strength depending on a number of 
factors, chiefly the area and magnitude of the high and 
the position of its crest, and the intensity and distance 
of the surrounding lows. The surface wind may then 
be too light to launch a kite until the pressure has begun 
to fall. Occasionally, though, a temporary interrup- 
tion of the stationary pressure may strengthen the sur- 
face wind sufliciently to start a flight — a circumstance 
the observer should be on the alert to take advantage of. 

If a flight has been started after a more or less continu- 
ous fall in pressure has set in, increasing winds may bo 
expected during the progress of the flight. The velocity 
to which the winds will rise in any given time will depend 
not only on the rate of fall in pressure, but also, in a sense, 
will vary inversely as the pressure. In other words, it 
will generally be found that the greater the ftiagnitudo 


of the retreating high the longer (in terms of hours) will 
the maximum intensity of the on-coming low be delayed. 
On the other hand, a slowly moving high, even though 
it be comparatively flat, appears effectively to delay the 
advance circulation of a following low. Shallow winds, 
above which it is difficult to raise the kites imless much 
lifting surface is used, are common in the rear of highs. 

If the pressure is low and stationary, the surface winds 
may be light, and under such circumstances one should 
resist the temptation to use large and many kites until 
the preceding fall in pressure has been ascertained. If 
the fall has been very slow and no very low level reached, 
this, together with the light surface w^inds, may be con- 
strued as indicating comparatively light winds to a fairly 
good height. If the pressure is quite low and the pre- 
ceding fall has been rapid, a more or less sudden rise in 
velocity may be looked for at some not very great alti- 
tude; or may accompany a sudden shift in direction. 

If a flight is made during a period of rapidly falling 
pressure, and the pressure is below normal, the winds 
will very likely be strong practically from the ground up ; 
in this case, if a flight is possible, it will naturally be 
limited to few kites. Ordinarily, strong winds do not 
preclude the possibility of a flight unless they attain gale 
force near the ground. Where the strength of the wind 
limits the number of kites to three or less, flights to 
nearly 3,000 meters above the ground may be obtained 
by rapid reeling out and without risk of materially 
increasing the pull on the reel-in since, as explained else- 
where, the Marvin-Hargrave kite is self-adjusting to 
strong winds. In such a case care should be taken not 
to reel out more wire than the kites can hold above the 
ground, bearing in mind that the wire will drop to a lower 
angular altitude as soon as reeling in commences. 

When the barometer is low and rising, the winds are 
likely to be more uniform in direction and velocity with 
altitude, and less given to abrupt changes, than when the 
pressure is low and falling. Much the same precautions 
should be observed in either phase of low pressure, 
although in the case of rising pressure there is smaller 
probability of the pull increasing after the highest possi- 
ble altitude has been attained, the supposition being that 
the winds have already reached their maximum. On 
the whole, it may be said that falling pressure presents 
more difffculties than rising pressure. Low pressure, 
owing to the complexities of cyclonic circulation, has 
more elements of danger than higli pressure. 

While the dilferent conditions of pressure mot with 
from day to day are, of course, iiflinite in number, their 
relation to the ])robable velocities may be summed up as 
depending on the barometric tendency, and the position 
of the centers of high and low pressure areas. The latter 
qualifying circumstance is the most dillicult to make 
(icductions from, in the absence of current weather maps, 
and all available sources of information should therefore 
be studied carefully to determine the probable direc- 
tion from the station of a near-by center of low pressure. 


INSTRUCTTONkS for aerolochoai. observers. 


35 


When tlio cliroction of movoineiit of a row {'oincidos with 
tlio direction of tl\c "radic'nt winds, tlu'rc is evidence that 
winds at the various altitudes average strongest, other 
things being equal, and that when such a condition is 
impeiuling the rise in velocities will be most rapid. The 
treml of the isobars can be estimated closely from the sur- 
face winds, the barogra{)h trace, and the aspect of the 
first kite launched after it is a few hundred meters high. 

In estimating the probable direction of the centers of 
high and low pressure from the station at the beginning 
of a flight, in the absence of other information, the ob- 
server should supplement his knowledge of the general 
laws of surface circulation with observations of the wind 
direction a few hundred meters above the ground. Un- 
less surface winds are quite strong and have biowm from 
a certain direction for some time they do not give con- 
clusive evidence of the direction of the pressure gradient, 
owing to the susceptibility of light winds to local topog- 
raphy and diurnal change in temperature. Judgment 
will therefore have to be deferred until the behavior of 
the first kite launched has been observed. 

With a little practice, conclusions concerning the pres- 
sure distribution can be arrived at that will be accurate 
enough for the purpose of kite flying. This refers more 
particularly to the cold season, w^hen pressure conditions 
and changes are sharply defined. With approaching 
warm weather the whole problem of analyzing pressure 
conditions becomes increasingly difficult; and unless some 
telegraphic information is available, one wall often be at 
a loss to know what to expect. This has its com])ensa- 
tion, however, in the comparative freedom from unsafe 
conditions, except such as are of a local nature, in summer 
weather. 

The trend of the isobars can be approximated by con- 
sidering the direction of the w'ind at that moderate alti- 
tude above the ground where surface friction is sur- 
mounted and to which the kites gradually veer. In 
LOWS and in the rear of mens, gradient winds will usually 
be found at only a few hundred meters above the ground. 
While their direction wdth reference to the isobars varies 
somewhat with the rate of movement of the low or uigu 
and their depth varies considerably in different quad- 
rants, it will be of aid to know' when Ihese gradient winds 
have been reached, considering that their direction is ap- 
proximately })arallel to the suifaee isobars, with low pres- 
sure to the left. Above these gradient directions the 
W'inds in a i.ow will ordinarily veer or po.ssibly back to 
the higher levels, depemding on whether the low is ap- 
proaehing or receding. In the fi’ont of a iinui the winds 
will often back from the ground up, no veering being 
apparent at any level. 

Olovds. — Low-lying dense clouds add to the perplexi- 
ties of kite flying. They are likely to be a menace in any 
wind direction and during any season of the year, more 
especially, however, with low pressure prevailing. Stra- 
tus clouds are characteristic as trouble i)reedcrs, and any 
indication of strato-cumulus blending into stratus should 


be reason for caution; and conversely, stratus breaking 
into strato-cumulus should bo considered encouraging. 
It is desirable, of course, to obtain a record of upper-air 
conditions in any cloud condition, but judgment should 
be used in deciding on the number of kites to expose when 
conditions seem threatening. In warm weather dense 
stratus are not necessarily dangerous unless they are 
moving rapidly and rain is falling or seems imminent. 
The combined effect of rain and strong wind often com- 
pletely crushes one* or two kites. It will sometimes tax 
the initiative of the flying force, when caught in such con- 
ditions, to limit the danger to one or two kites and avoid 
excessive pull on the wire. If a flight is started during 
the prevalence of such conditions, reeling out and the 
launching of kites should proceed cautiously until the 
absence of any strong wdnd in the cloud layer is assured. 

During periods of more or less continuous rain, the 
most opportune time for making a flight without risk of 
the kites collapsing appears to be about midday, when 
evaporation from the clouds often causes a lull in the rain. 

Dense fog usually occurs with light surface wind. It 
has been the experience of the wTiter, in the middle West, 
wiien flying in dense fogs, that if the wire and dynamom- 
eter show' that the kites have entered a stronger wind 
of different direction a few hundred meters above the 
ground, it can be taken for granted that the fog sheet 
lias been surmounted, and need give no further concern. 
In other conditions of fog, the kites will fly at a low 
angular altitude, become w'atcr-logged and heavier, and 
eventually fall to the ground, unless reeled in soon after 
the flight has been started. A useful precaution to 
observe wiien the kites are flying at a low' angle in a fog 
is to take frequent readings of atmospheric voltage, in 
order to watch for the possibility of the wire touching the 
ground. 

In the cold season of northern latitudes an additional 
difliculty connected with Hying in heavy clouds lies in the 
accumulation of ice or frost on the kites and wire in 
amounts that may bo sulficient to cause them to fall in 
spite of raj)id reeling in. This danger is-present only 
when the surface temjieraturc is in the neighborhood of 
freezing or soniew'hat below'. When any of the lower 
types of (iouils prevail with this state of temperature, a 
cei tain amount of ice will almost always form on the w'ire, 
but cxces.sive deposits on wire and kites w'ill occur oidy 
when the sk}' is overcast or nearly so, and the circum- 
stances favor a j)rolonged ex[)osure of the clouds. 'Phe 
deposit is caused by minute globules of the subcooled 
water, .sometimes having a temperature as low as — 10° C., 
freezing on contact w'ith the solid surfac^es — a process that 
is facilitated by wind. J'here is but little danger of more 
than a light coating of ice on the wire when snow is 
falling freely, but moist snow' with wind may cause an 
excessive pull in the same manner us rain w'ith wind. 

If, after rising above a strong surface wind, tlie kites 
float on (op of or in the clomls, tliis fact will be indicated 
by the dynamometer. With freezing temperature, un- 


36 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


less the kites can be thrown up higher by reeling in, 
accumulation of ice will proceed over a long approxi- 
mately horizontal line of kites and wire and gradually 
cause them to settle down. A common condition attend- 
ing a period of rising pressure in winter is a strong cold 
under-running northerly wind, near the summit of which 
dense clouds form. Often the wind above the under- 
running cold current is too light to lift the kites free of the 
influence of the clouds, with the result that the heavily 
laden kites will fall into the strong lower wind and cause 
excessive pull. If the dynamometer indicates that the 
kites are flying at a good angle, a condition of great 
cloud depth may be present, the possible consequence of 
which will be indicated only by a lowering in the angle of 
the wire and a lessening of whatever atmospheric electric 
potential might previously have been recorded. A normal 
potential will dwindle almost to zero as the wire becomes 
increasingly bulky with ice or frost and lower in angle. 
Dynamometer readings can be relied upon only to indi- 
cate the approximate angle of the kites before they and 
the wire have had time to become heavily coated, after 
which the pull is inclined to be deceptive, owing to their 
increased weight enabling the kites to present a more 
nearly normal surface to the wind. 

When in the judgment of the observer the conditions 
seem to be favorable for the formation of ice or frost- 
work on the wire, it is a good plan to reel out as rapidly 
as is consistent with a good ascensional rate of the kites, 
thereby penetrating the cloud layer with minimum 
exposure thereto. A good rule to observe in any threat- 
ening cloud condition is to begin the final reeling in when 
the pull is well on the safe side of 200 pounds in order to 
leave a margin of safety for any possible increase in pull 
later on. 

The fact that deposits of rime (frostwork) on the wire, 
which have been observed as large as half an inch in 
diameter,® are most pronounced when snow is not actually 
falling, seems to indicate the lack of some final stage 
necessary for precipitation, when all the other essentials 
for condensation are present. An interesting circum- 
stance bearing on this point is the evidence, in numerous 
records of kite flights, that the beginning of precipitation 
is often preceded or attended by a sudden increase in the 
electric charge on the wire. 

Diurnal series . — A knowledge of pressure distribution 
over the country is of considerable helj) when attempting 
to make 24 to 36 hour series of flights, as the series arc 
often ended or interrupted by the wind becoming too 
light or too strong, or the weatlicr becoming stormy. 
There are a number of conditions that have been observed 
at Drexel, Nebr., to be favorable for the steady winds 
and fair weather desirable for an unbroken series of 
flights of fairly uniform altitudes. These conditions arc 
perhaps typical of considerable of the interior portion of 
the country. 


An area of high pressure receding to the east generally 
causes a prolonged, somewhat vigorous drainage of air 
from a southerly direction in the lower levels, and more 
or less steady, lighter winds from a westerly direction 
in the higher levels. If the pressure is quite high and 
the surface wind is strong enough to begin a series while 
still in the crest of the high, or as soon as the pressure 
begins to fall, the probabilities are for favorable flying 
weather for 24 to 36 hours or more. 

An area of low pressure, centered north of the station 
and moving eastward, is often attended by generally fair 
weather and continuous moderate southerly winds in the 
lower levels. At higher levels, the winds will probably 
be strong and veer from southwesterly to westerly or 
northwesterly, as the low drifts eastward. 

In the winter excellent series of flights are possible 
when a pronounced high-pressure area is approaching 
from the west or northwest. In this condition, however, 
a series may have to be started while the weather is still 
cloudy, in order to obtain at least 24 hours continuous 
record, since the crest of the high, with its attendant 
light surface winds, often comes not long after the weather 
clears. 

Thunderstorms . — Bince a thunderstorm is largely a 
local phenomenon, no general rules can be laid down 
for detecting its approach. No precaution seems ordi- 
narily of avail other than listening attentively for thun- 
der on days when conditions seem to favor thunder- 
storm development, and frequently breaking the elec- 
trostatic ground for evidence of "flash” discharges. By 
"flash” discharge is meant a momentary increase in the 
potential that causes intermittent sparks at the ground 
gap and are synclu'onous with discharges of lightning in 
the vicinity. As such irregular discharges may be an 
accompaniment of storms passing the station as well as 
of one approaching it, and arc, moreover, often observed 
when the sky is mostly clear, they are not, in the majority 
of cases, necessarily a warning of unsafe conditions. 
Flashes of lightning on the horizon should be considered 
in connection with the observed tlrift of such clouds as 
are visible. The })robable course of the outlying storm 
may thus be determined. 

A possible indication of thunderstorm development 
may be inferred from the strong vertical currents of great 
depth that are frexjucntly evident in warm weather during 
kite nights. If these are associated with high surface 
humidity and increasing C'u. or St. Cu. clouds, conditions 
arc probably ri])c for thunderstorm formation. In gen- 
eral, when tlie sky is overcast during the warm season, 
an erratic action of the electrostatic voltmeter, or thunder, 
should 1)0 considered a warning. 

Flights have on a number of occasions been caught in 
thunderstorms, and, while the records during such 
storms are extremely valuable, the danger of personal 
injury and damage to ecpiipment is too great to justify 
other than unavoidable flights xinder such conditions. 
The danger to the person in thunderstorms lies chielly in 


0 Mo. Wea. Rev. Supplement No. 10 (Aerology No. 5), p. 5. 


INSTRUCTIONS FOR yVEROLOGK^AL OBSERVERS. 


37 


the landing of secondary kites. The person removing 
the branch wire by means of wliich a secondary kite is 
attacliod to the main lino shmdd bo provided witli r\d)ber 
gloves and boots, and under no circumstances shoidd he 
stand on the ground. The person landing the kite 
should also bo provided with rubber gloves and boots, 
but when the cord to which the secondary kite is at- 
tached is wet, and the danger seems very great, no at- 
tempt should be made to land the kite other than to cut 
the cord and allow the kite to go adrift. It is of course 
hardly necessary to add that the reel should be grounded 
as thoroughly as it is possible to do so. 

Local conditions . — The continuity of daily flights will 
depend a great deal on the vigilance and energy of the 
station force, as on many days when comparative calm 
prevails a brief interval of breeze will be suffleient to 
carry the kites into steady sustaining winds aloft. 

Although surface velocities are higher in daytime than 
at night, this fact, particularly in warm weather, has 
often the opposite significance in kite flying. This is 
undoubtedly explained by the fact that convectional 
currents, even though they may cause a slight accelera- 
tion of surface movement, have a damping influence on 
the normal increase of wind velocity with altitude, and, 
moreover, constitute a mechanical hindrance to success- 
ful launching of kites. Strong convectional currents tend 
to cause continual confusion of kites, cords, and wire. 
This sometimes becomes so aggravated as to necessitate 
reeling in to prevent the kites from falling to the ground. 
Flights, therefore, should be started early enough on 
summer mornings to assure a height of a thousand 
meters or more before convectional currents are well 
under way. 

Sometimes on clear, quiet days, during which a flight 
has been impossible, the kites will readily go up about 
sunset, or when nocturnal cooling sets in. It completes 
the often-observed paradox, just mentioned, of flying 
conditions and surface wind, as in such instances the 
station anemometer is very likely to record lower veloc- 
ities than at any time during the day. A plausible 
explanation is that the sudden cessation of convection 
currents permits the normal tendency for horizontal 
air movement to come into play and that the intense 
radiation at that hour confines the stagnant air to those 
very lowest levels immediately above the ground. At 
Drcxel this condition has been fretpiently observed and 
taken advantage of, although it has been found to be 
decidedly peculiar to south winds.’ 

The foregoing paragraj)!! illustrates one of the many 
causes that operate to mask the ))ossibility of a flight 
from indications of the station anemometer. Notwith- 
standing that it requires a velocity of at least 5 m.p.s. 
to sustain a kite and several hundred meters of wire, 
velocities as low as 1.5 m.p.s. need be no discouragement 
to those attempting a flight. 

’ KeoMo. Wea. Rev., Supplement No. 8 (Aerology No. 4), p. 7, and Mo. Wea. Rev., 
Juno, 1919, 47: 373. 


lircahwjoys . — Experience in kite flying will be valuable 
in the measure that it develops not only prescience of 
danger, but confidence in action when doubtful condi- 
tions obtain. Overcautiousness may spoil or curtail 
many a flight that would otherwise have been safe and 
high. On the whole, it may be said that dangerous 
conditions for kite flying, apart from those that are 
clearly evident from surface conditions, are exceptional. 
Therefore, whenever weather conditions on the ground 
permit, a flight can generally be started with all assurance 
of safe return of the kites. 

Breakaways may be divided into two classes — (a) 
accidental and (b) those caused by overloading the wire. 
The former may be largely prevented by attention to 
the condition of the wire, while the latter may be sub- 
divided into a number of causes as follows: 

1. Kites floating on top of a shallow wind, or flying 
at a low angle, and finally rising into strong wind aloft. 

2. Reehng out too rapidly to permit the dynamometer 
to show increase in velocity aloft. 

3. Wind increasing rapidly soon after beginning to reel in. 

4. Too long exposure of kites to damp, fast-moving clouds. 

5. In rarer cases, kites caught in a thunderstorm or 
sudden squall. 

To these may be added the occasional risk of kites 
falling on account of accumulations of ice, and the 
unsteady effects of light winds or convection currents. 

The prevention of trouble from all these causes will, 
to a large extent, be under the control of the field force. 
Cause 3 will call for the greatest caution on the part of 
the observer in charge of the flight. Winds increasing 
during the progress of a flight generally accompany 
falling pressure. The rise in wind velocity attending the 
approach of a low-pressure center has often been observed 
to begin at some moderate altitude, and subsequently 
become more general. Close attention to the dynamom- 
eter while launching secondary kites will give early 
evidence of increasing wind force aloft. 

9. REDUCING RECORDS FOR TELEGRAPHIC MESSAGE. 

For the purpose of forecasting it is desirable that the 
daily observations made by kite flights at the different 
stations be as nearly simultaneous as jiossible and that 
(he reports of observations be received at the forecast 
centers without delay. At all the aerological stations, 
therefore, kite flights are made whenever possible during 
the morning hours, that time of day being preferable for 
taking observations to bo used in forecasting and most 
suitable for favorable flying conditions. As soon as 
possible after the comf)letion of each daily flight a quick 
computation of the record is made and the value of the 
various elements at suitable elevations is enciphered 
and telegraphed to the designated forecasting centers. 
At present these centers arc Washington and Chicago. 

The data telegraphed are altitinle, pressure, tem- 
perature, wind direction and velocity, and humidity, 
both at the surface and aloft. Altitudes are rej)orted 


38 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


in meters above sea level, pressures in millibars, tempera- 
tures in centij^rade, wind velocity in meters per second, 
wind direction to eight points of the compass, and rela- 
tive humidities in percentages. 

The pressure, tem])erature, wind velocity, and humidity 
are readily computed from the records by means of the 
knoAvn factors of the instrument used. Wind direction 
is recorded by eye observation during the flight. In 
computing altitude only the factors of pressure and 
average temperature of the air column are used, the 
latter being approximated by simply taldng the mean 
of the temperature aloft and at the surface. Form 
No. 1103-Aer. is used for the computations. This is 
very similar to Form No. 1102-Aer. (Table 9, section 
10), the only difference being that Form No. 1103-Aer. 
has extra spaces for the entry of code words. 

The observations are telegraphed only when heights 
equaling or exceeding 500 meters above the ground are 
attained, since ordinarily conditions below that level 
can be assumed from surface observations and the 
weather map. As most kite observations extend to 
about 3,000 meters or higher above the ground the ele- 
vations for which the values of the elements are com- 
puted and telegraphed are generally those of 1,000, 
2,000, and 3,000 or more meters above the surface. 
The data for these levels usually convey in the abstract 
a complete survey of the atmosphere from the ground 
to the highest altitude sounded since ordinarily the 
changes in the values of temperature, wind force and 
direction, and humidity from one level to the next are 
uniform enough to admit of close approximation for any 
intervening elevation by interpolation. Very often, 
however, particularly in winter, marked inversions in 
temperature and other abrupt deviations from the normal 
altitude change in the elements are observed. When 
such abnormalities occur and cover a sufficient range in 
altitude to distinguish them from diurnal, local, or other 
temporary efl’ects, the levels for which data are to be 
reported by telegraph are chosen with a view to indi- 
cating these conditions clearly to the forecast centers. 

To give brevity to the messages, to make them easier 
to send and less liable to error, etc., a code is used. 
Briefly this code consists of a list of common words and 
names, selected for their sequence of key consonants 
and vowels in order to give any desired numerical or other 
value to one or more syllables. The key letters consist 
of nine consonants and the five vowels, representing 
multiples of 10 up to 90, and the even digits from 0 to 8, 
respectively. Eight of these consonants have an alter- 
nate meaning for the cardinal points of the compass. 
As the key letters arc few in number the code words are 
readily translatable at sight; and as the position of the 
word in the message determines the clement to which it 
refers, making possible a repetition of the same word in 
a message, a comparatively small list of code words with 
a few arbitrary words serves to encipher any desired 
weather message. 


The code adopted for reporting free-air conditions is 
an adaptation of the Weather Bureau Code, 1916 edition, 
regularly used in transmitting surface observations. 
The following key and examples show how this adapta- 
tion is accomplished: 

First word. — Time of observation, from pages 95-97 of 
Weather Bureau Code Book, 1916 edition. Example: 
Each — 8:40 a. m. 

Second word. — Altitude to nearest 10 m.eters, from 
pages 54-59, “T” words. Examples: Taggings — 1,470 
meters; Titus — 3,910 meters. 

Third and fovrth words. — Actual pressure aloft and at 
the surface in millibars. Third word gives hundreds of 
millibars aloft; first syllable of fourth word gives the 
two following figures in pi’cssure aloft; second syllable, 
ditto at surface, from pages 26-35. Examples: Six 
sacred — pressure aloft, 682 millibars; at surface, 974 
millibars. (Note. — At most stations the surfixce pressure 
is between 900 and 999 millibars; for all such the one 
word is sufficient. If, however, this pressure is 800+ or 
1,000+ the -words “surface eight” or “surface ten,” as 
the case may be, should follow the words expressing 
pressure.) 

Fifth and sixth words. — Temperatures, °C, aloft and at 
surface, from pages 54-59; “S” words, above zero; “T” 
words, below zero. Examples: Tardiness — Subdues — 
Temperature aloft, —12°. 7 C.; at surface, +2°.l C. 

Seventh and eighth words. — Wind direction and velocity, 
meters per second, aloft and at surface, from pages 26-35. 
First letter of each word gives direction; second letter 
gives first figure in velocity when latter is above 9.9 
meters per second, (a, e, i, o equal, respectively, 10 + , 
20 + , 30 + , 40 + ) ; first two letters of second syllable 
give the last two figures in the velocity to tenths of a 
meter per second. Example: Nemuel — Guarantee — 
aloft, SW. — 25.0, meters per second; surface, SE. — 7.2 
meters per second. 

Ninth word. — Relative humidity aloft and at surface, 
pages 26-35. Example: Fumosity — aloft, 30 per cent; 
at surface, 58 per cent. 

The following excerpt from a telegraphic message, 
referring to one upper air level, illustrates the code and 
its translation: 

Example of message: Full — Tinselly — Six Doremus — 
Tutoring — Subastral — Resale — Surname — Nonology. 

Translation: Time of observation, 11 a. m. Altitude, 
3,840 meters. Pressure aloft, 628 millibars; at surf.aco, 
974 millibars. 'i'emi)craturo aloft, —9°. 8 (k Tempera- 
ture at surface, 1°.2 C. Wind aloft, west, 28. 2 m. p. s. 
Wind at surface, northwest, 6.2 m. p. s. Ilumiility 
aloft, 68 per cent; at surface, 68 per cent. 

10. FINAL REDUC'JTON OF RECORDS. 

As indicated in the preceding section, the kite records 
are partially reduced for telegraphic purposes at the 
stations. This includes the computation of base-line 
values and of the meteorological elements at a few 


INSTRUCTIONS FOR AFROr.OGICAL OBSERVP^RS. 


39 


selected altitudes. The records themselves are thou divided by the time in hours, and from this a s(;al(! for 

forwarded to WashingtoTi for liiial reduction. This linal several hours is made. This is divided into minutes so 

reduction is made in such detail as to furnish what may tliat, knowing the time at whicii tlie pens were placed on 

be described as a complete history of the llight; i. e., the record sheet, for example, 0:43 a. rn. (fig. 32), the 

“levels” or points on the traces winch show changes in time scale is so placed tliat the l)oginning of the trace is 
the gradients (or rates of change with altitude) of the opposite the proper time on that scale (43 minutes in this 

different elements ai’e computed. This computation, case). The positions of the hour lines are then noted and 

although not diflicult, is comparatively laborious because an arc drawn for each one. In doing this care should be 

of the fact that altitudes are not directly observed, but taken that the proper lengths of pen arms and ceiiters 

must be determined by means of the hypsometric equa- of arcs, as previously determined, are used. 



tion, into which enter several variable factors. A detailed 
account of all the steps necessary in this reduction of 
kite records is given in the following pages. 

Hour lines . — Because the regulation of the clocks of 
the various instruments can not be kept identical “hour 
lines” must be drawn on each record. This is accom- 
plished by di’awing arcs, as described in section 7 and as 
indicated in figure 32. The [lositions of these hour lines 
are determitied with the aid of a spc'cial time scale. (See 
fig. 30.) The length of the record, in millimeters, is 


Base lines . — Before values can bo computed from 
cither the tenqierature, pressure, or lunnidity traces it 
is necessary to estahlisli “base lines.” This is done by 
drawing a light pencil line along one of the horizontal 
printed lines on the record sheet, choosing that lino which 
is nearest the ends of the trace under consideration. The 
value of the temperature base line is obtained by taking 
the number of divisions, to tenths — the beginning of the 
trace is above or below the base line— and multiplying 
this number by the proper scale value or “factor.” 


40 


INSTEUCTIONS FOE AEEOLOGICAL OBSEEVEES. 


This result is applied to the surface temperature recorded 
at the corresponding time. The operation is repeated at 
the end of the trace, and the mean of these two values 
is used as the temperature of the base line. 

The humidity base line is established in a similar 
manner with a slight difference in the method of convert- 
ing the ordinates to per cent. Instead of multiplying 
by a constant scale value, as was done for the temperature, 
scales are used, the construction of which is described 
in section 7. 

The pressure base line is determined by noting the 
number of divisions, to tenths — the beginning of the trace 
is above or below the base line — taking the corresponding 
niimber of millibars from a table constructed for the 
instrument in use; and applying this result to the surface 
pressure in millibars recorded at the time for which the 
readings were taken. To obtain the value at the end of 
the trace similar steps are taken with the addition of a 
correction to compensate for the change in surface tem- 
perature that usually occurs between the beginning and 
the end of the flight. This is a correction for instrumental 
error due to incomplete compensation of the aneroid for 
temperature and acts in the same direction for nearly 
all instruments, i. e., a rise in temperature causes the 
pressure element to register too low, while a fall in tem- 
perature acts in the opposite direction. The amount of 
change in degrees centigrade necessary for a correction 
of 0.1 division in pressure is predetermined by tests- 
From this it is obvious that when the pressure trace is 
below the base line and the temperature has/aZZen suffi- 
ciently for a correction of 0.2 of a division this amount 
will be added to the pressure ordiriate, since the latter 
is 0.2 of a division too high. The mean of the values 
found for the beginning and end of the trace determines 
the value of the base line. 

Form No. 1108-Aer. is used in computing base-line 
values. (See Table 8.) In the typical record (fig. 32) 
the value of the temperature ordinate at 6:54 a. m. is 
3.1 divisions below the base line. This is multiplied by 
the scale value for the instrument, 0.93, and found to 
be 2°. 9 C. To this is added the surface temperature 
recorded at this time, obtaining 3°. 4 C. At the time 
pens were last lifted, 11:06 a. m., the ordinate value is 
3.4 divisions above the base line. Multiplying this by 
the scale value gives 3°. 2 C., and subtracting from the 
recorded surface temperature gives 3°. 6 C. The mean 
of 3°. 4 C. and 3°. 6 C. is the desired base-line value. 

On the pressure trace the ordinate at 6 :54 a. m. is 0.3 of 
a division below the base line. From the tabular values 
this is found to be equivalent to 3.4 millibars. Adding 3.4 
to the surface pressure for 6 :54 a. m. gives 988.2. At 1 1 :06 
a. m. the ordinate value is 0.9 of a division below the 
base-line. The surface temperature has risen during the 
interval, 6:54 to 11:06 a. m. from 0°.5 C. to 6°. 8 C. or 
6°. 3 C.; this temperature change requires a correction 
of 0.3 of a division to be subtracted from the pressure 
ordinate making the corrected pressure ordinate 0.6, 
which is equivalent to 6.7 millibars. Since this has a 


negative sign with respect to the base line, it is added 
to 982.1, surface pressure at 11:06 a. m., and the result 
is 988.8. The mean of 988.2 and 988.8 is the desired 
base-line value. 

Table 8. 

[Form No. llOS-Aer.] 

U. S. DEPARTMENT OF AGRICULTURE, WEATHER BUREAU. 

Base-Line Values. 

Station, 


Date, 

Meteorograph No Flight No. 


Time, 

a. m. 

Temperature. 


Corrected 

values. 

6:54 

Ordinate 

—3 1 



Temperature 

0.5 



Ord. value ... 

2.9 

3,4 


11:06 

Ordinate 

3.4 


Temperature 

6.8 



Ord. 'value 

3.2 





3.6 





3.5 


Pressure. 



6:54 

Ordinate 

-0.3 



Pressure 

9S4, 8 



Ord. value 

3.4 


11:06 

Ordinate 

—0.9 

9SS. 2 



0.3 




—0.6 



Pressure 

982. 1 




6.7 





9SS.8 





988.5 


Humidity. 



6:54 

Ordinate 

2.0 



87 





11:06 


0.5 

77 

69 




Snalft valiift 







73 





71 


The ordinate value on the humidity trace at 6:54 a. m. 
is 2.0 divisions above the base line. With a surface rela- 
tive humidity of 87 per cent at this time, the humidity 
scale gives a value of 69 per cent. The end of the trace 
shows an ordinate value of 0.5 division above the base 
line. Applying this to the humidity scale, using a sur- 
face relative humidity of 77 per cent, gives 73 per cent. 
The mean of 69 per cent and 73 per cent is the desired 
base-line value. The agreement of the base-line values 
obtained at the beginning and end of the traces should 
be carefully observed, and when these values are found 
to vary considerably for several successive llights, the 
instrument should be retested. 

Placing and computing levels . — ddic levels are indicated 
by arrows placed at synchronous jioints on all four traces 
according to the following rules: 

1. In general, arrows are desired near the beginning 
and end of the llight, not moi'e that three or four divi- 
sions below the pressure base line; this being usually on 
the first and last “stop.”” (But note suggestion 3 in 
this connection.) 


* By ".itop” is meant a fi-rnimi to Interval ilnrlng which the kites are allowed I o remain 
at soiDO doflnlto hoight; 1. e., the wlro is neither reeled out nor reeled in. 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


41 


2. Between these arrows should bo placed (on, prefer- 
ably at the end of, “stops” when possible) at intervals 
of 5 to S divisions (or, under exceptionally favorable con- 
ditions, at even greater intervals when the scale value is 
less than 1.4 mb. for 0.1 division). 

3. Arrows should always be placed, irrespective of 
“stops,” at the immediate beginning and ending of 
temperature inversions and isothermal conditions, also 
at the lowest point in the pressure trace and highest 
and lowest points in the temperature trace. 

4. Abnormal changes in the humidity record should 
be indicated by arrows. Since the humidity element has 
been found in some cases to lag somewhat, the arrow 
should be placed at the point believed to be in agree- 
ment with the temperature and pressure curves. Indi- 
vidual judgment must be exercised in such cases. (See 
arrow at 9:19 a. m., fig. 32.) 


5. Wherever a decided rate of change in tlu; ternpcTa- 
turo trace, with respect to the pressure curve, occurs 
indicating a change in the tcinj)erature gradient, arrows 
should be placed to show the beginning and ending of 
this change. 

6. In general, a straight interpolation between two 
arrows should show the true conditions, and arrows 
should be placed so as to bring out this fact. 

7. In entering the time of the arrow in ink on the data 
sheet, it is desirable to make the time agree with that of 
the surface reading when a difference of a minute or less 
is found, so that a comparison of the altitude obtained 
from the angle may be made. 

A computation sheet, Form No. 1102-Aer., Table 9, 
is used for each level, and the time of the arrow is entered 
in the proper place on this sheet. Many^ of these neces- 
sary entries will be readily understood by inspection. 


Table 9. 

[Form No. 1102-Aer.] 

U. S. DEPARTMENT OF AGRICULTURE, WEATHER BUREAU. 

Kite-Record Computation Sheet. 

Station Date Time m. 



42 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


The pressure, temperature, relative humidity, and wind 
direction at the surface are taken from the data sheet, 
Table 10. When necessary, interpolations are made 
between the adjacent times occurring on this sheet. The 
surface wind velocity is taken from Form No. 1017-Met’l. 
(W. B. triple register record) for the required time and 
converted to meters per second. The base line values of 
pressure, temperature, and relative humidity are entered 
in their proper places. The ordinates of these elements, 
read to tenths, are entered with their proper signs with 
respect to the base line. The temperature ordinate is 
multiplied by the proper factor and the result applied to 
the base-line value. This gives the value in degrees C. 
of the point on the temperature trace and is entered as 
the temperature aloft in its proper place on the sheet. 

The relative humidity aloft is determined by applying 
the ordinate to the base-line value, using for this purpose 
the proper humidity scale, as described in section 7. 


The temperature correction for pressure is obtained by 
taking the difference in temperature aloft at the time 
of the level and the initial surface temperature at the 
time taken for obtaining this same correction in comput- 
ing the pressure base line. With this correction applied, 
the pressure ordinate is converted into millibars from 
the proper table and the result applied to the base-line 
value. The value thus obtained is entered as the pres- 
sure aloft. 

The wind direction aloft is taken from the data sheet, 
proper interpolation being made when a “level” occurs 
between two observations. 

The vapor pressure is determined by the use of tables 
giving the aqueous vapor pressure in millibars for various 
temperatures. The proper value, as found in this table, 
is multiplied by the relative humidity already determined, 
and the result is the vapor pressure for the level in 
question. (See Table 17.) 


(Form No. 1107 -Aer. 


station 

Observer at reel, 


Table 10. 

?. DEPARTMENT OF AGRICCITCRE, WE.ATHER BUREAU. 
Record of Kite Flight. 

Meteorograph, 

; at record, 


Date, 


Miscellaneous data. 

Time. 

Wire 

out. 

Angle. 

Thermometers. 

Relative 

humid- 

ity. 

Wind direction. 

Voltmeter. 

Weather notes. 

Dry. 

Wet. 

Surface. 

Aloft. 

Scale. 

Volts. 


a. m. 

Meiers. 


. 


% 







6:43 



0.6 

-0.2 

86 

ese. 




4 St. Cu. ssw. 


6:50 



0.5 

—0. 2 

87 

ese. 









0. 5 

—0.2 

87 

ese. 






7;0o 



0. 5 

-0.2 

87 

ese. 






7:11 

300 

58 

0.6 

—0.2 

86 

ese. 

se. 


0 



7:16 

700 

39 

0.8 

0.0 

86 

ese. 

s. 


565 



7:21 

700 

52 

0.6 

0.0 

89 

ese. 

s. 


565 



7:29 

1,400 

20 

0.6 

0.0 

89 

ese. 

s. 


950 



7;34 


38 

0.6 

0.0 

89 

ese. 

sse. 


1,.5()0 



7:47 

2,400 

35 

0.8 

0. 1 

87 

ese. 

sse. 


2,200 



7:52 

31 

1.0 

0.3 

88 

ese. 

sse. 


2,000 



8.12 

4,000 

18 

1.6 

0.8 

86 

ese. 

sse. 


3, 400 



8;21 

26 

1.6 

0.8 

SO 

sc. 

s. 


5, 400 



8:27 

(t 

33 

1.8 

1.0 


se. 

ssw. 


5,600 

No. 43 entered St. Cu. base at 8:30, ^ .32°, 4,200 m 


8:38 

5,000 


1.8 

1.0 

86 

se. 

ssw. 


6,000 

out. 


S.-iO 









Stop 

8:50 

6, 000 


2.2 

1.2 

83 

se. 

ssw. 


6,900 



8:55 


2.4 

1 4 

83 

se. 

ssw. 


7,400 


Stop 

9:06 

6, .SOO 


2.8 

1.8 

84 

se. 

ssw. 


7,000 

7 St. Cu. ssw. 


9:11 


2.8 

1.8 

84 

se. 

ssw. 


7,500 



9; 19 

6,000 


3.0 

2.0 

84 

se. 

sw. 





9:26 

5^000 


3.6 

2. 4 

82 

se. 

sw. 





9:35 

4,000 


4. 2 

3.0 

82 

sc. 

sw. 


5, 200 



9:47 

3' 200 


4.0 

2.8 

82 

se. 

ssw. 


4 ; 000 


Reel in 

9.50 


42 

3.8 

2.7 

83 

sc. 

ssw. 


4,300 

No. 45 out of St. Cu. base at 9:.50, ^ 37°, 3,200 m. 


10:00 

2,400 

53 

4.4 

3.0 

79 

se. 

ssw. 


2, ,500 

out. 


10:05 

41 

4.6 

3.2 

SO 

se. 

s. 


2, 500 



10. II 











10:18 

1,400 

51 

5. 4 

3.7 

77 

sc. 

.s. 


1,200 



10:23 

43 

5. 8 

4.2 

79 

se. 

s. 


1 ; 200 



I0.'29 












10:32 

700 

51 

5.8 

4.2 

79 

sse. 

s. 





10:37 

n 

33 

6.0 

4. 4 

79 

sse. 



490 



lo.m 












10:42 

300 

51 

5.8 

4.2 

79 

se. 

sc. 


0 



10:47 


43 

6. 6 

4.8 

77 

so. 

so. 


0 



I0;53 



6.6 

4.0 

79 

se. 




9 St. Cu. ssw. 


10:55 

1 

0.6 

4. 9 

78 

se. 






11:06 

1 

6.8 

5.0 

77 

se. 







i 










BAROMETRIC PRESSURE. 



0:00 3. 

7:00 a. 

8:00 a. 

9:00 a. 

10:00 a. 


29. 08 

29. OS 

29.06 

20.01 

29. 02 


984. 8 

984. 8 

984. 1 

983. 4 

982. 7 







The wind velocity aloft is obtained by measuring the the indicated time, with a wind-velocity scale used by the 
length of one complete mark, i. c., one complete cycle of Weather Bureau in determining velocities as recorded on 
the recording pen, as operated by the cam, occurring at Form No. 1017. The value thus obtained is multijilied 


TNSTRTK^TIONS FOR AKROLOOTCAL OBSERVERS. 


43 


l\y a factor determined from tests of the instrument. To 
this result a reeling correetion is applied and consists in 
delermininpj the rate in meters per second at which reeling 
has taken place. This correction is added for reeling out 
and subtracted for reeling in. Printed tables liaving 
minutes of time and meters of wire as arguments give 
the amount of this correction. (See Table 16.) 

nyi>sometric equation . — After the data mentioned above 
have been computed there remains to be determined 
the altitude of these levels. The determination of this is 
based upon the hypsometric formula: 

Z- A- (1 +°0) (f:o.Wj)(' 1 

in which h = height of the upper station. 

7i,Q = height of the lower station. 

Z =h-h^. 

p = atmospheric pressure at the upper station. 
Pq = atmospheric pressure at the lower station. 
R =mean radius of the earth. 

0 =mean temperature of the air column be- 
^ tween the altitudes h and 

e =mean pressure of acpieous vapor in the air 
column. 

h =mean barometric pressure of the air 
column . 

K = barometric constant (18,400). 
a = coefficient of the expansion of air. 
g = standard value of gravity (980.665 dynes), 
y I, = local value of gravity. 

A detailed explanation of the derivation of the con- 
stants and the several variables used in this formula will 
be found in the Smithsonian Meteorological Tables, 1918 
edition, pages xxx to lii. 

The lower half of the computation sheet. Table 9, per- 
tains to a direct application of this formula. 

Za and Zs are obtained individually from a printed 
table (Table 13) the values in which are based on the 

expression, 18,400 log . where B is the barometric 

pressure. Z^ is then subtracted from Za and the value 
thus obtained is the ap[)roximatc altitude of the level 
above the surface. To this value there must be applied 
corrections for temperature, humidity, latitude, and 
gravity. 

The table for the fletermination of altitudes from j)res- 
sure is based upon a mean temperature of the air column 
of 0° C. Whenever the mean temperature has another 
value, a correction is applied by multiplying the approxi- 
mate altitude by a factor a =0.00367 0, in which 0.00367 
is the coefficient of the expansion of air and 0 the mean 
air temperature. This correction is added when the 
mean temperature is above 0° C. and subtracted when it 
is below 0° C. P’or values of a corresponding to different 
values of 0, see Table 14. 

For the lowest computed altitude of a flight the mean 
air temperature is simply half the sum of the tempera- 


tures aloft and at the surface. 1'his method is not used 
for higlier levels; it would bo correct, if the temperature 
gradient were uniform at all altitudes, but this is rarely 
the case, and it is therefore necessary to take into consid- 
eration these variations iti the gradient. In order to do 
this the mean temperatures for successive levels are 
weighted according to the altitude intervals between 
them, these differences being considered only to the near- 
est hundred meters. For example, if the first level is at a 
height h, the mean air temperature is In the case 

” 2" ■ 

of the next higher level at a height h' , the mean temper- 
ature is 

V 

In computing kite records it is necessary also to take 
into consideration the changes that occur in the tem- 
peratm-e at the surface and for some distance above the 
surface during the flight. If all the observations were 
made at one time there would be no such correction, 
but in kite flights this is never the case. The correction 
then is essentially one of time. The height to which the 
increase or decrease of temperature extends depends 
largely upon the diathermance of the lower strata, and 
therefore upon the extent of convectional activity. To 
determine this limiting height it is necessary to plot 
the temperatures as observed at various altitudes 
during the ascent and descent. These lines will meet 
at some point and that point is accepted as the height 
to which tbe surface warming or cooling extends. 

In figure 33, suppose that at 8 a. m. is the surface 
temperature, fa that at some height h; at 9 a. m., 4 , is 
the surface temperature, 4' that at some height h'-, at 
10 a. m., 4" is the surface temperature, 4" that at some 
height h" . The mean air temperature for the level at 

8 a. m. is Now, if we applied no surface-tern- 

perature correction the mean air temperature for the 
higher level at 9 a. m. would be 

-Hh’-h) ( 

V 


'J'his would give an entirely erroneous value, for during 
tbe interval 8 a. m. to 9 a. m. the surface tempera- 
ture has changed to 4' and that at the intermediate 
height h, to some value x. Tbe correct mean air 
teinj)erature would be 

h' 

but we do not know this value x. Wo can only 
assume that the change in temperature at the height 
h and at all other altitudes from the surface to the 
the point of intersection of the lines (in this case at the 
heiglit h') is a proportional one. Wo then obtain tho 


44 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


mean air temperature by correcting for this lime change 
in temperature and the corrected value is 

V ■ 

For any level below the point of intersection of the lines, 
the altitude to which the surface temperature correction 
is applied is the altitude of the level itself. For altitudes 
greater than the point of intersection of the lines this 
limiting height is the one used. 

The values of Q (mean temperature of air column) 
between levels are computed, beginning at the surface 



Fio. 33. — Diagram showing method of determining the mean temperature of the air 

column. 


and continuing upward to the highest level; then again 
working upward, through the descent, from the surface 
to the highest. The value of 0, for the highest level, is 
considered as the mean of the two vidues thus obtained 
for this level. 

The correction for humidity is determined from the 
following arrangement of exy)ressions taken from the 


hypsometric formula, 


1 

2 


/ 0.378^ 
\ 0.00367. 


and gives the result 


in terms of temperature. This value is included in that 
used to obtain the final temperature-correction factor, 


this latter being multiplied by Za - Z^ and the result then 
added to Za — Zgwhen the temperature is above 0°C., 
and subtracted when it is below 0°C. (See Table 15.) 

The correction for latitude and gravity is determined 
from the following terms taken from the h 3 ^psometric 
formula. 

This correction with respect to latitude is predetermined 
for each station and therefore will vary only as regards 
the value of Zj. The amount of correction applied is 
readily obtained from a table and is additive. This special 
table is made up for each station and is based upon 
Tables 62 and 63, 1918 edition, Smithsonian Institution 
Meteorological Tables. To the value of Z add the station 
elevation above sea level. 

The altitude of the kite carrying the instrument is 
also obtained trigonometrically whenever the level 
occurs at a time when a theodolite reading is made. 
This is determined by the expression li — l (sin 4>), where 
A is the vertical height, Z, the length of wire out in 
meters and cj), the angular altitude of the kite. It has 
been found that on the average a deduction of about 2 
per cent must be made from the altitude obtained in 
this way to allow for the sag in wire, number of kites 
out, etc. This altitude is used principally as a check 
on the former. 

The altitudes of observed values of electric potential 
are computed trigonometrically whenever possible, but in 
those flights made at night or when the kites are obscured 
by clouds it is necessary to employ another method. 
The pressure ordinate at the time at which the potential 
reading was made is corrected for temperature, and with 
this corrected ordinate those two levels are taken which 
occur immediately before and after the time of the 
potential reading. Using the corrected pressure ordi- 
nates of these levels, the altitude of the potential reading 
is directly interpolated, since the altitude varies inversely 
as the pressure or, rather, approximately so, for the 
comparatively short intervals between two levels. 
Form No. 1104-Aer., Table 11, is used for computing the 
electric potential data. 

Tabulation . — The data are now ready for tabulation 
and Form No. 1105-Aer., Table 12, is used for this 
purpose. The first entry is taken from the data sheet 
and gives the values observed at the time at which the 
instrument kite is launched, the altitude of the station 
above sea level being entered as the first altitude. 
Between the computed levels spaces are left for inter- 
polated levels at altitudes above sea level 250 meters 
apart, exce])t that the intervals are increased to 500 
meters for altitudes greater than 1,500 meters above sea 
level. The last entry is taken from the data sheet at 
the time the head kite is landed. In the first and last 
entries the data for both the surface and aloft are iden- 
tical. For the computed levels, the surface data are 
entered to the left of the doul)lo line and the data aloft 
to the right. 


45 


INiSTKITCTlONS FOR AEROLOGICAL OBSERVERS. 


Tadle 11. 

[Form No. llOl-Aer.] u. s. DEi’AUTMiiNT or aoricultuke, weather bureau. 

Altitudes at Times of Electric Potential Ukadinqs. 
Station, Date, 



7:11 

7:21 

7:34 

7:52 

8:27 

8:38 

8:55 








21.0 

27.5 







. 1 

. 1 







. 20.9 

27.6 




Same 



-1.2 

-7.0 




as 



— 1. 1 

-6.5 




7:34 



3.5 

3.5 




level. 



2.4 

-3.0 

Initial T 





0.5 

0.5 







1.9 

-2.5 



938 

1,191 

1,007 

2,000 

2,536 

5,000 

2,417 

3,041 

7,400 


0 

565 

1,500 

6; 000 






9:11 

9:35 

9:50 

10:05 

10:23 

10:37 

10 47 



28.5 

27.0 







.2 

. 1 







28.7 

27.1 







-8.0 

—7.0 







—7.9 

—6.5 

9:50 






3.5 

3.5 

level. 






-4.4 

-3.0 






0.5 

0.5 







-3.9 

-2.5 







3,272 

7,500 

3,086 

5,200 

2,458 

1,940 

1,331 

770 

598 


4,300 

2,500 

1,200 

490 

0 




[Form No. 1105-Aer.] 
Station, 


Table 12. 

u. s. department of agriculture, weather bureau. 

Free- Air Data From Kite Fughts. 

Meteorograph, Date, 


Surface. 


At different heights above sea. 


Time. 

Pres- 

sure. 

Tem- 

pera- 

ture. 

Rela- 

tive 

humid- 

ity. 

Wind. 

Alti- 

tude. 

Pres- 

sure. 

Tem- 

pera- 

ture. 

At 

100 m. 

Humidity. 

Wind. 

Potential. 

Remarks. 

Direc- 

tion. 

Veloc- 

ity. 

Rela- 

tive. 

Vapor 

pres- 

sure. 

Direc- 

tion. 

Veloc- 

ity. 

Grav- 

ity. 

Elec- 

tric. 

a. m. 

mb. 

°C. 

% 


771 . p.8. 

m. 

mb. 

°C. 


% 

mb. 


in. p.s. 

lO^ergs. 

Volfs. 


7:06 

984.7 

0. 5 

87 

ese. 

5.4 

398 

984.7 

0.5 


87 

5. 51 

ese. 

5.i 



4/10 St. Cu. ssw.; changing to 7/10 St. Cu. 







500 

973.0 

1.0 


89 

5.84 

se. 

6.6 










750 

94 . 3.0 

2. 1 


92 

6.53 

s. 

9.4 


0 

by end of flight. 

7:29 

984.5 

0.6 

89 

ese. 

4.5 

799 

936.5 

2.3 

-0. 45 

93 

6. 71 

s. 

9.9 








1,000 

914.2 

4.8 


75 

6. 45 

sse. 

11.8 


560 


7:34 

984.4 

0.6 

89 

ese. 

4.9 

l' 191 

892.4 

7.2 

— 1. 25 

58 

5. 89 


13.6 









i'250 

886.0 

7.1 


58 

5.85 

sse. 

13.3 


1,500 








I'SOO 

800.0 

6.9 


59 

5.87 

sse. 

12.0 




8:12 

98-1.0 

1.6 

86 

ese. 

5.8 

1,,587 

852.5 

6.8 

0.11 

59 

5.83 

sse. 

11.7 


2,000 

8:30 and 2,300 m. at 9:50 a. m. 







2,000 

808.9 

3.8 


39 

3. 13 

s. 

16.2 




8:21 

983.9 

1.6 

86 

se. 

6.3 

2, 070 

801.2 

3.3 

0.70 

36 

2. 79 

s. 

16.9 




8:40 

983.6 

1.9 

86 

se. 

6.3 

2, 487 

761.0 

1.6 

0.41 

100 

6.86 

ssw. 

19.0 


6,000 








2, 500 

700. 1 

1.5 


99 

6. 74 

ssw. 

19.0 










3 ' 000 

714. 0 

—2.3 


80 

4.03 


18.7 


7,400 








3 ' 500 

070. 1 

—6. 1 


60 

2. 19 

sw. 

18.3 


7^500 


9:19 

983.2 

3.0 

84 

se. 

5.4 

3,723 

651. 1 

-7.8 

0.78 

51 

1.61 

sw. 

18.2 










3^500 

670. 1 

—6.0 


58 

2 . 13 

sw. 

18.3 










3 ' 000 

713. 2 

-2. 1 


72 

3.69 

ssw. 

18.6 


5,200 








2,500 

759. 2 

1.9 


87 

6.09 

ssw. 

18.9 



9:.50 

982.8 

3.8 

83 

se. 

6.3 

2,4.58 

703. 0 

2.2 

0. 49 

88 

6.30 

ssw. 

18.9 


4,300 








2, 0(K) 

807. 4 

4.4 


53 

4.43 

s. 

17.6 


2,500 


10:11 

982.6 

5.0 

79 

se. 

5.8 

1,778 

829. 8 

. 5.5 

0.24 

36 

3.25 

s. 

16.9 










1^500 

859. 1 

6.2 


52 

4.93 

8. 

16.3 



1,200 








l'2.50 

885.2 

6.8 


67 

6. 62 


15.9 




10:29 

982.4 

5.8 

79 

sse. 

5.4 

1,121 

898.8 

7.1 

-0.93 

75 

7. 57 

s. 

15.6 










I'fKK) 

913. 3 

6.0 


78 

7.29 

s. 

13.9 










'750 

942.0 

3.6 


85 

6. 72 

sse. 

10.2 



490 


10:40 

982.3 

5.9 

79 

se. 

4.9 

671 

949. 0 

2.9 

1.34 

87 

6.54 

sse. 

9. 1 











500 

971.0 

5.2 


82 

7. 25 

se. 

6.8 


0 


10:53 

982.2 

6.6 

79 

se. 

5.4 

396 

982.2 

0.0 


79 

7.09 

so. 

5.4 





Linear interpolations are made for tlie intermediate 
values of temperature, relative humidity, wind direction, 
and velocity. The atmospheric pressures for these 
levels are determined by plottinoj the pressures for the 
calculated levels, using the altitudes as ordinates and 
the pressures as abscissae, d'his is necessary because in 
this instance the interpolation is not a linear one hut 
approaches a logarithmic curve. This, however, is 
dependent upon the temperature at the various levels. 


The column headed 


At 

100 


is the change in temperature 


per 100 meters, or the tem|)eraturc gradient. The 
gradient values arc obtained by dividing the diU’ercnce 
in temperature between two adjacent levels by the 
number of hundred meters dilforence in their elevation. 


and the results are given to two decimal places. The 
gradient is positive when the temperature decreases with 
altitiule, and negative when the the temperature increases 
with altitude. 

The vapor pressures are obtained from the corre- 
sponding temperature and relative humidity as in the 
case of the computed levels. (See Table 17.) 

The values of electric potential are entered to the 
nearest 10 opposite the altitudes nearest which they occur. 

Under “ Remarks” are recorded all meteorological phe- 
nomena observed during the High t, including cloud changes, 
halos, thunderstorms, beginning and ending of ])recipi- 
tation, etc. Whenever kites arc observed to enter or 
leave the cloud base, a reading of the theodolite is made 
and the altitude above sea level computed; the result is 


46 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 


expressed to the nearest even 50 meters below the com- 
puted value. This result is entered under “Remarks” 
with a brief statement, together with a record of the 
kind and direction of the clouds. 

11. REDUCTION TABLES. 

Tables 13 to 18, inclusive, are regularly used in the 
reduction of every free-air record obtained by means of 
kites. Tables 13, 14, and 15 are exactl}* the same as 
Tables 57, 58, and 61 of the 1918 edition, wSmithsonian 
Meteorological Tables, and a description of their use 
may be found in the introduction of that work. 

The values in Table 16 were obtained by dividing the 
number of meters indicated at the tops of the columns by 
the number of seconds in the minutes listed in the 
extreme left-hand column. 

Table 17 corresponds to Tables 71 and 72 in the 
Smithsonian Meteorological Tables, 1918 edition, except 


that vapor pressures are expressed in millibars instead 
of millimeters. 

Table 18 gives values of relative humidity, or per- 
centage of saturation, for air temperatures from — 39° C. 
to +44° C. (side argument) and for depressions of the 
wet-bulb thermometer at 0.1° C. intervals (top argu- 
ment). Thus, only a single interpolation is necessary. 
The values have been computed for a barometric pressure 
of 990 mb., this being approximately the average 
pressure at the kite stations now maintained by the 
Weather Bureau. When the air is very dry, errors of 
1 or 2 per cent in the relative humidity are possible with 
pressures markedly differing from the mean here adopted, 
but such instances are infrequent, and even then the 
errors are no greater than those of observation. Hence, 
it is deemed unnecessary to use two or tliree different 
sets of tables, the one, computed for an average pressure, 
being sufliciently accurate for all practical purposes. 


Table 13. — Determination of heights by the barometer. 

/ 1013.3\ 

(Values of 18400 log ) 



0 

1 

2 

3 

4 

5 

6 

7 

8 

9 




Pressure 












P. P. 


(mb.) 


















METERS. 








500 

5645 

5629 

5613 

5597 

5581 

55G5 

5549 

5533 

5518 

5502 


19 

15 


510 

54‘'i6 

5471 

5455 

5439 

5424 

5408 

5393 

5377 

5362 

5346 

0. 1 

2 

2 

520 

5331 

5316 

5300 

5285 

5270 

5255 

5239 

5224 

5209 

5194 

.2 

3 

3 

5J0 

5179 

5164 

5149 

5134 

5119 

5104 

5089 

5074 

5059 

5044 

.3 

5 

4 

540 

5030 

5015 

5000 

4985 

4971 

4956 

4941 

4927 

4912 

4898 

.4 

6 

6 

550 

4883 

4868 

4854 

4839 

4825 

4.S11 

4796 

■1782 

4708 

4753 

. 5 

8 

8 

560 

4739 

4725 

4710 

4696 

4682 

4668 

4654 

4640 

4626 

4612 

.6 

10 

9 

570 

4598 

4583 

4569 

4556 

4542 

4528 

4514 

4.500 

44,S6 

4472 

.7 

11 

10 

5S0 

4459 

4445 

4431 

■4417 

4-404 

4390 

4376 

4303 

4349 

4335 

.8 

13 

12 

590 

4322 

4308 

4295 

4281 

■1268 

4254 

■1241 

4228 

4214 

4201 

.9 

14 

14 

600 

4188 

4174 

4161 

4148 

4134 

4121 

4108 

4095 

4082 

4069 


14 

13 


610 

4056 

4042 

4029 

4016 

4003 

3990 

3977 

3984 

3951 

3939 

0. 1 

1 

1 

620 

3926 

3913 

3900 

3887 

3874 

3861 

3849 

3836 

3823 

3810 

.2 

3 

3 

650 

3798 

3785 

3772 

3760 

3747 

3735 

3722 

3709 

3697 

3684 

.3 

4 

4 

640 

3672 

3659 

3647 

3635 

3622 

3610 

3597 

3585 

3573 

3500 

.4 

6 

5 

650 

3.548 

3536 

3523 

3511 

3499 

3487 

3475 

3462 

3450 

3138 

. 5 

7 

6 

660 

3426 

3414 

3402 

3390 

3378 

3.366 

3354 

3342 

3330 

3318 

.6 

S 

8 

670 

3306 

3294 

3282 

3270 

3258 

3246 

3235 

3223 

3211 

3199 

. 7 

10 

9 

680 

3187 

3176 

3164 

3152 

3141 

3129 

3117 

3106 

3094 

30S2 

.8 

11 

10 

690 

3071 

3059 

3048 

3036 

3025 

3013 

3002 

2990 

2979 

2967 

.9 

13 

12 

700 

2956 

2944 

2933 

2922 

2910 

2899 

2888 

2.S76 

2865 

2854 


L2 

u 




710 

2842 

2,831 

2820 

2809 

2798 

27.86 

2775 

2764 

2753 

2742 

0. 1 

1 

1 

720 

2731 

2720 

2708 

2697 

26S6 

2675 

2664 

2653 

2642 

2631 

.2 

2 

2 

750 

2621 

2609 

2599 

2588 

2577 

2566 

2555 

2544 

2533 

2523 

.3 

4 

3 

740 

2512 

2501 

2490 

2479 

2)69 

2458 

2447 

2437 

2426 

2415 

.4 

5 

4 

750 

2405 

2394 

23.83 

237.3 

2362 

23.51 

2341 

2330 

2320 

2309 

. 5 

6 

0 

760 

2299 

2288 

2278 

2267 

2257 

2246 

2236 

2225 

2215 

2205 

.6 

7 

7 

770 

2194 

2184 

2173 

216,3 

21,53 

2142 

2132 

2122 

2112 

2101 

. 7 

8 

8 

780 

2091 

2081 

2071 

2060 

2050 

2040 

2030 

2020 

2009 

1999 

.S 

10 

9 

790 

1989 

1979 

1969 

19.59 

1949 

1939 

1929 

1919 

1909 

1899 

.9 

11 

10 

800 

1889 

1879 

1869 

1,859 

1.S49 

1839 

1829 

1819 

1.S09 

1799 


9 

s 




810 

1789 

1780 

1770 

1760 

17,50 

1740 

1731 

1721 

1711 

1701 

0. 1 

1 

1 

820 

1692 

1682 

1672 

1062 

1653 

161.3 

1033 

1623 

lf)l4 

1004 

.2 


2 

850 

1595 

1585 

1575 

1566 

1556 

1.547 

1537 

1527 

1518 

1508 


3 

2 

840 

1499 

1489 

14, SO 

1470 

MCI 

14.51 

14-12 

1433 

1423 

1414 

.4 

-1 

3 

850 

1404 

1.395 

1,386 

1370 

1.367 

13.57 

13-4S 

1339 

1329 

1320 

. 5 

4 

■1 

860 

1311 

1302 

1292 

1283 

1274 

1204 

1255 

1210 

1237 

1228 

.6 

5 

5 

870 

1218 

1209 

1200 

1191 

1182 

1173 

1164 

11.51 

1115 

1136 

.7 

6 

6 

880 

1127 

1118 

1109 

1100 

1091 

1082 

1073 

1064 

10.55 

1046 

.8 

7 

6 

890 

1037 

1028 

1019 

1010 

1001 

992 

983 

974 

965 

956 

.9 

8 

7 

900 

948 

939 

930 

921 

912 

90.3 

894 

886 

877 

S6S 


7 





910 

8,59 

.850 

842 

833 

824 

81.5 

807 

798 

789 

781 

0. 1 

1 


920 

772 

763 

755 

7‘10 

737 

729 

720 

711 

703 

094 

.2 

1 


950 

686 

677 

668 

000 

051 

643 

634 

626 

617 

60S 

.3 

2 


940 

600 

.592 

583 

575 

500 

558 

549 

541 

532 

524 

.4 

3 


950 

516 

.507 

499 

490 

482 

474 

405 

4.57 

448 

440 

. 5 

4 


960 

432 

424 

415 

407 

399 

,390 

382 

374 

365 

357 

.6 

4 


970 

349 

341 

332 

324 

310 

308 

300 

292 

2.S3 

275 

.7 

5 


980 

267 

2.59 

2,51 

243 

2.34 

226 

218 

210 

202 

194 

.s 

6 


990 

186 

178 

170 

162 

1.54 

146 

138 

130 

122 

114 

.9 

6 


1000 

106 

98 

90 

82 

74 

66 

58 

50 

42 

34 




1010 

26 

18 

10 

2 

-6 

-13 

-21 

-29 

-.37 

—15 




1020 

-.53 

-61 

-68 

-76 

-84 

-92 

-UK) 

-107 

-115 

-123 




1050 

-131 

-138 

-MO 

-1.54 

-162 

-169 

-177 

-1,85 

-192 

-200 




1040 

-208 

-216 

-223 

-231 

-238 

-240 

-254 

-261 

-269 

-277 





INSTRUCTIONS FOR AEROLOGKUL OBSERVERS 


47 


Table 14. — Temperature correction factor, (a.) 

(Multiply values of Z .— Z , by a; add correction when moan temperature Is above 0 ° C ; subtract when below 0 ° C .) 


Moan 

Temp . 

0. 

.0 

.1 

.2 

.3 

.4 

.5 

.6 

.7 

.8 

.9 

°C. 

a 

a 

a 

a 

a 

a 

a 

a 

a 

a 

0 

0.000 

0.000 

0.001 

0. 001 

0.001 

0.002 

0.002 

0.003 

0.003 

0.003 

1 

.004 

.004 

.004 

.005 

.005 

.006 

.006 

.006 

.007 

.007 

2 

.007 

.008 

.008 

.008 

.009 

.009 

.010 

.010 

.010 

.oil 

3 

.011 

.011 

.012 

.012 

.012 

.013 

.013 

.014 

.014 

.014 

4 

.015 

.015 

.015 

.016 

.016 

.017 

.017 

.017 

.018 

.018 

5 

.018 

.019 

.019 

.019 

.020 

.020 

.021 

.021 

.021 

.022 

6 

.022 

.022 

.023 

.023 

.023 

.024 

.024 

.025 

.025 

.025 

7 

.026 

.026 

.026 

.027 

.027 

.028 

.028 

.028 

.029 

.029 

8 

.029 

.030 

.030 

.030 

.031 

.031 

.032 

.032 

.032 

.033 

9 

.033 

.033 

.034 

.034 

.034 

.035 

.035 

.036 

.036 

.036 

10 

.017 

.037 

.037 

.038 

.038 

.039 

.039 

.039 

.040 

.040 

11 

.040 

.041 

.041 

.041 

.042 

.042 

.043 

.043 

.043 

.044 

12 

.044 

.044 

.045 

.045 

.046 

.046 

.046 

.047 

.047 

.047 

13 

.048 

.048 

.048 

.049 

.049 

.050 

.050 

.050 

.051 

.051 

14 

.051 

.052 

.052 

.052 

.053 

.053 

.054 

.054 

.054 

.055 

15 

.055 

.055 

.056 

.056 

.057 

.057 

.057 

.058 

.058 

.058 

16 

.059 

.059 

.059 

.060 

.060 

.061 

.061 

.061 

.062 

.062 

17 

.062 

.063 

.063 

.063 

.064 

.064 

.065 

.065 

.065 

.066 

18 

.066 

.066 

.067 

.067 

.068 

.068 

.068 

.069 

.069 

.069 

19 

.070 

.070 

.070 

.071 

.071 

.072 

.072 

.072 

.073 

.073 

20 

.073 

.074 

.074 

.075 

. 075 

.075 

.076 

.076 

.076 

.077 

21 

.077 

.077 

.078 

.078 

.079 

.079 

.079 

.080 

.080 

.080 

22 

.081 

.081 

.081 

.082 

.082 

.083 

.083 

.083 

.084 

.084 

23 

.084 

.085 

.085 

.086 

.086 

.086 

.087 

.087 

.087 

.088 

24 

.088 

.088 

.089 

.089 

.090 

.090 

.090 

.091 

.091 

.091 

25 

• .092 

.092 

,092 

.093 

.093 

.094 

.094 

.094 

.095 

.095 

26 

.095 

.096 

.096 

.097 

.097 

.097 

.098 

.098 

.098 

.099 

27 

.099 

.099 

.100 

.100 

.101 

.101 

.101 

.102 

.102 

.102 

28 

.103 

.103 

.103 

.104 

.104 

.105 

.105 

.105 

.106 

.106 

29 

.106 

.107 

.107 

.108 

.108 

.108 

.109 

.109 

.109 

.110 

30 

.110 

.110 

.111 

.111 

.112 

.112 

. 112 

.113 

.113 

.113 

31 

.114 

.114 

.115 

.115 

.115 

.116 

.116 

.116 

.117 

.117 

32 

.117 

.118 

.118 

.119 

.119 

.119 

.120 

.120 

.120 

.121 

33 

.121 

.121 

.122 

.122 

.123 

.123 

.123 

.124 

.124 

.124 

34 

.125 

.125 

.126 

.126 

.126 

.127 

.127 

.127 

.128 

.128 

35 

.128 

.129 

.129 

.130 

.130 

.130 

.131 

.131 

.131 

.132 

36 

.132 

.132 

.133 

.133 

.134 

.134 

.134 

.135 

.135 

.135 

37 

.136 

.136 

.137 

.137 

.137 

.138 

.138 

.138 

.139 

.139 

38 

.139 

.140 

.140 

.141 

.141 

.141 

.142 

.142 

.142 

.143 

39 

.143 

.143 

.144 

.144 

.145 

.145 

. 145 

.146 

.146 

.146 


48 


INiSTRUCTIONS FOR AEROLOGICAL OBSERVERS 

Table 15. — Humidity correction — Add to mean temperature. 


Air 

VAPOR PRESSURE ( MB .) 
















( mb .) 

0.5 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

20 

30 

40 


° C . 

“ C . 

° C . 

” 0 . 

° C . 

“ U . 

° C . 

° C . 


° C . 

° c . 


° C . 

° C . 

1040 

0.0 

0.0 

0 . 1 

0. 1 

0.2 

0.2 

0.3 

0.3 

0.4 

0.4 

0.5 

1.0 

1. 5 

2.0 

1020 

.0 

. 1 

. 1 

.2 

.2 

.3 

.3 

.4 

.4 

.5 

.5 

1.0 

1 . 5 

2.0 

1000 

.0 

. 1 

. 1 

.2 

.2 

.3 

.3 

.4 

.4 

.5 

.5 

1.0 

1.5 

2.1 

980 

.0 

. 1 

. 1 

.2 

.2 

.3 

.3 

.4 

.4 

.5 

.5 

1.1 

1.6 

2. 1 

960 

.0 

.1 

. 1 

.2 

.2 

.3 

.3 

.4 

.4 

.5 

.5 

1. 1 

1.6 

2.1 

940 

.0 

.1 

. 1 

.2 

. 2 

.3 

.3 

.4 

.4 

.5 

.5 

1.1 

1.6 

3.2 

920 

.0 

. 1 

. 1 

.2 

.2 

.3 

.3 

.4 

.4 

.5 

.6 

1. 1 

1.7 

2.2 

900 

.0 

. 1 

. 1 

.2 

.2 

.3 

.3 

.4 

.5 

.5 

.6 

1. 1 

1.7 

2.3 

880 

.0 

.1 

. 1 

.2 

.2 

.3 

.4 

.4 

.5 

.5 

.6 

1.2 

1.8 

2.3 

S 60 

.0 

. 1 

, 1 

.2 

.2 

.3 

.4 

.4 

.5 

.5 

.6 

1.2 

1.8 

2.4 

840 

.0 

. 1 

. 1 

.2 

.2 

.3 

.4 

.4 

.5 

.6 

.6 

1.2 

1.8 


820 

.0 

. 1 

. 1 

.2 

.3 

.3 

.4 

.4 

.5 

.6 

.6 

1.3 

1.9 


800 

.0 

.1 

. 1 

.2 

.3 

.3 

.4 

.5 

.5 

.6 

.6 

1.3 

1.9 


780 

.0 

.1 

. 1 

.2 

.3 

.3 

.4 

.5 

.5 

.6 

.7 

1.3 

2.0 


760 

.0 

. I 

. 1 

.2 

.3 

.3 

.4 

.5 

.5 

.6 

.7 

1.4 



740 

,0 

. 1 

. 1 

.2 

.3 

.3 

.4 

.5 

.6 

.6 

.7 

1.4 



720 

.0 

. 1 

. 1 


.3 

.4 

.4 

.5 

.6 

.6 

.7 

1.4 



700 

.0 

. 1 

. 1 

.2 

.3 

.4 

.4 

.5 

.6 

.7 

.7 

1.5 



680 

.0 

.1 

.2 

.2 

.3 

.4 

.5 

.5 

.6 

.7 

.8 




660 

.0 

. 1 

.2 

.2 

.3 

.4 

.5 

.5 

.6 

.7 

.8 




640 

.0 

. 1 

. 2 

.2 

.3 

.4 

.5 

.6 

.6 

.7 

.8 




620 

.0 

. 1 

.2 

.2 

.3 

.4 

.5 

.6 

.7 

.7 





600 

.0 

.1 

.2 

.3 

.3 

.4 

.5 

.6 

.7 

.8 





580 

.0 

. 1 

.2 

.3 

.4 

.4 

.5 

.6 

.7 

.8 





560 

.0 

.1 

jy 

.3 

.4 

.5 

.6 

.6 

.7 






540 

.0 

.1 

.2 

.3 

.4 

.5 

.6 

.7 

.8 



• 



520 

.0 

.1 

.2 

.3 

.4 

. 5 

.6 

.7 

.8 






500 

. 1 

.1 

.2 

.3 

.4 

. 5 

.6 

.7 







480 

. 1 

.1 

.2 

.3 

.4 

.5 

.6 

.8 







460 

. 1 

.1 

.2 

.3 

.4 

.6 

.7 

.8 







440 

. 1 

. 1 

.2 

.4 

.5 

.6 

.7 








420 

. 1 

. 1 

.2 

.4 

.5 

.6 

.7 








400 

. 1 

.1 

.3 

.4 

.5 

.6 

.8 








380 

. 1 

. 1 

.3 

.4 

.5 

.7 









360 

. 1 

. 1 

.3 

.4 

.6 

.7 









340 

. 1 

.2 

.3 

.5 

.6 

.8 









320 

. 1 

.2 

.3 

.5 

.6 










300 

. 1 

. 2 

.3 

.5 

. 7 










280 

.1 

.2 

.4 

.6 

.7 










260 

. 1 

.2 

.4 

.6 











240 

. 1 


.4 

.6 











220 

. 1 

.2 

.5 

.7 











200 

. 1 

.3 

.5 












180 

. 1 

.3 

.6 












160 

.2 

.3 

.6 












140 

.2 

.4 













120 

.2 

.4 













100 

.3 

.5 













80 

.3 














60 

.4 














40 

.6 














20 

1.3 














10 

2.6 

1 














INSTRUCTIONS FOR AEROLO(U(L\L OBSERVERS 


49 


Table 16. — Correction for wind velocity. 

Ukelino ouT-t-. [In nieter.s per spcond.) Ukeijno in — 


TIMK AND DISTANCE IIKTWEEN OIJSEUVATIONS. 


Minutes. 

m. 

500 

in. 

*600 

in. 

700 

m. 

800 

TU. 

900 

m. 

1,000 

in. 

MOO 

m. 

1,200 

m. 

1,300 

m. 

1,400 

m. 

1,500 

m. 

1,600 

ni. 

1,700 

m. 

1,800 

in. 

1,900 

m. 

2,000 

3 

2.S 

3.3 















4 

2. 1 

2.5 

2.9 

3.3 













5 

1.7 

2.0 

2.3 

2.7 

3.0 

3.3 











6 

1. 4 

1.7 

2.0 

2.2 

2.5 

2.8 

3.0 

3.3 









7 

1. 2 

1.4 

1.7 

1.9 

2.2 

2.4 

2.6 

2.8 

3. 1 

3. .3 







8 

1.0 

1.2 

1.5 

1.7 

1.9 

2. 1 

2.3 

2.5 

2.7 

2.9 

3. 1 

3.3 





9 

0.9 

1. 1 

1.3 

1.5 

1. 7 

1.8 

2.0 

2.2 

2.4 

2.6 

2.8 

3.0 

,3.2 

3.3 



10 

0.8 

1.0 

1.2 

1.3 

1.5 

1.7 

1.8 

2.0 

2.2 

2.3 

2.5 

2.7 

2.8 

3.0 

.3.2 

3.3 

II 

0.8 

0.9 

1. 1 

1.2 

1.4 

1.5 

1.7 

1.8 

2.0 

2. 1 

2.3 

2.4 

2.6 

2.7 

2.9 

3.0 

12 

0.7 

0.8 

1.0 

1. 1 

1.2 

1.4 

1.5 

1.7 

1.8 

2.0 

2. 1 

2.2 

2.4 

2.5 

2.6 

2.8 

U 

0.6 

0.8 

0.9 

1.0 

1.2 

1.3 

1.4 

1. 5 

1.7 

1.8 

1.9 

2.0 

2.2 

2.3 

2.4 

2.6 

14 

0.6 

0.7 

0.8 

1.0 

1. 1 

1.2 

1.3 

1.4 

1.6 

1.7 

1.8 

1.9 

2.0 

2.2 

2.3 

2.4 

15 

0.6 

0.7 

0.8 

0.9 

1.0 

1.1 

1.2 

1.3 

1.4 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

2.2 

16 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

1. 1 

1.2 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

17 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

1.1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

18 

0. 5 

0.6 

0.6 

0.7 

0.8 

0.9 

1.0 

1.1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.8 

19 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

1.0 

1. 1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

20 

0.4 

0.5 

0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.1 

1.2 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

21 


0.5 

0.6 

0.6 

0.7 

0.8 

0.9 

1.0 

1.0 

1.1 

1.2 

1.3 

1.4 

1.4 

1.5 

1.6 

22 




0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.1 

1. 1 

1.2 

1.3 

1.4 

1.4 

1.5 

23 




0.6 

0.6 

0.7 

0.8 

0.9 

1.0 

1.0 

1.1 

1.2 

1.2 

1, 3 

1.4 


24 




0.6 

0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.0 

1. 1 

1. 9 . 

1.2 

1.3 

1.4 

25 




0.5 

0.6 

0.7 

0.7 

0.8 

0.9 

0.9 

1.0 

1. 1 

1. 1 

1.2 

1.3 

1.3 

26 





0.6 

0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.0 

1. 1 

1.2 

1.2 

U3 

27 





0.6 

0.6 

0.7 

0.7 

0.8 

0.9 

0.9 

1.0 

1.0 

1. 1 

1.2 

1.2 

28 





0.5 

0.6 

0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.0 

1.0 

1. 1 

1.2 

29 






0.6 

0.6 

0.7 

0.8 

0.8 

0.9 

1.0 

1.0 

1.0 

1. 1 

1.2 

30 






0.6 

0.6 

0.7 

0.7 

0.8 

0.8 

0.9 

1.0 

1.0 

1.0 

1. 1 

31 






0.5 

0.6 

0.6 

0.7 

0.8 

0.8 

0.9 

0.9 

1.0 

1.0 

1. 1 

32 







0.6 

0.6 

0.7 

0. 7 

0.8 

0.8 

0.9 

0. 9 

1.0 

1.0 

33 







0.6 

0.6 

0.6 

0.7 

0.8 

0.8 

0.8 

0.9 

1.0 

1.0 

34 







0.5 

0.6 

0.6 

0.7 

0.7 

0.8 

0.8 

0.9 

0.9 

1.0 

35 








0.6 

0.6 

0.7 

0.7 

0.8 

0.8 

0.8 

0.9 

1.0 

36 








0.6 

0.6 

0.6 

0.7 

0. 7 

0. 8 

0.8 

0.9 

0. 9 

37 








0.5 

0.6 

0.6 

0. 7 

0, 7 

0. 8 

0.8 

0.8 

0. 9 

38 









0.6 

0.6 

0.6 

0. 7 

0.8 

0.8 

0.8 

0.9 

39 









0.6 

0.6 

0.6 

0. 7 

0.7 

0.8 

0.8 

0. 8 

40 









0.5 

0.6 

0.6 

0.7 

0.7 

0.8 

0.8 

0.8 


40329—21 4 


50 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS 

Table 17. — Pressure of aqueous vapor. 


Temp . 

.0 

.1 

.2 

.3 

.4 

.5 

.6 

.7 

.8 

.9 

° C . 





MILLIBARS . 





-34 

0.25 

0.25 

0.24 

0.24 

0.24 

0.24 

0.24 

0.23 

0.23 

0.23 

-33 

.28 

.28 

.27 

.27 

.27 

.26 

.26 

.26 

.26 

.25 

-32 

.31 

.31 

.30 

.30 

.30 

.30 

.29 

.29 

.28 

.28 

-31 

.34 

.34 

.34 

.34 

.33 

.33 

.32 

.32 

.32 

.31 

-30 

.38 

.38 

.38 

.37 

.37 

.36 

.36 

.38 

.35 

.35 

-29 

.43 

.42 

.42 

.41 

.41 

.40 

.40 

.40 

.39 

.39 

-28 

.47 

.47 

.46 

.46 

.45 

.45 

.44 

.44 

.44 

.43 

-27 

.52 

.52 

..51 

.51 

.50 

. 50 

.49 

.49 

.4 H 

.48 

-26 

.58 

.57 

.57 

.56 

.56 

. 55 

.54 

.54 

..53 

.53 

-25 

.64 

.63 

.63 

.62 

.62 

.61 

.60 

.60 

.59 

.58 

-24 

.71 

.70 

.69 

.69 

.68 

.67 

.67 

.66 

.65 

.65 

-23 

.78 

. // 

.77 

.76 

.75 

.74 

.74 

.73 

.72 

.71 

-22 

.86 

.85 

.84 

.84 

.83 

.82 

.81 

.80 

.80 

.79 

-21 

.95 

.94 

.93 

.92 

.91 

.90 

.89 

.89 

.88 

.87 

-20 

1.04 

1.03 

1.02 

1. 01 

1.00 

1.00 

.99 

.98 

.97 

.96 

-19 

1.15 

1. 14 

1. 13 

1. 12 

1.11 

1. 10 

1. 09 

1. 07 

1.06 

1. 05 

-18 

1.26 

1.25 

1.24 

1.23 

1.22 

1. 20 

1.19 

1. 18 

1.17 

1. 16 

-!7 

1.39 

1.37 

1.36 

1. 35 

1.34 

1. 32 

1.31 

1.30 

1. 29 

1.27 

-16 

1. 52 

1..51 

1.49 

1.48 

1. 47 

1.45 

1.44 

1.43 

1. 41 

1. 40 

-IS 

1.67 

1.65 

1. 64 

1.62 

1.61 

1.59 

1.58 

1.57 

1. 55 

1.54 

-14 

1.83 

1.81 

1. 80 

1.78 

1.76 

1.75 

1.73 

1.72 

1. 70 

1.69 

-13 

2.00 

1.99 

1.97 

1.95 

1.93 

1.92 

1.90 

1.88 

1.86 

1. .85 

-12 

2.19 

2.17 

2.15 

2. 13 

2.12 

2. 10 

2.08 

2.06 

2.04 

2.02 

-11 

2.40 

2.38 

2.35 

2.33 

2.31 

2. 29 

2.27 

2.25 

2.23 

2.21 

-10 

2.62 

2.60 

2.57 

2.55 

2.53 

2. 51 

2.48 

2.46 

2.44 

2.42 

- 9 

2.86 

2.83 

2.81 

2.78 

2.76 

2.74 

2.71 

2.69 

2.67 

2. 64 

- 8 

3. 12 

3.09 

3. 07 

3.04 

3. 01 

2.99 

2.96 

2.93 

2.91 

2.88 

- 7 

3.40 

3.37 

3. 34 

3.31 

3. 29 

3.26 

3.23 

3. 20 

.3.17 

3. 15 

- 6 

3. 70 

3. 67 

3. 64 

3.61 

3. 58 

3. 55 

3.52 

3. 19 

3.46 

3.43 

- 5 

4.03 

4.00 

3. 97 

3.93 

3.90 

3.87 

3.83 

3.80 

3. 77 

3.74 

- 4 

4.39 

4. 35 

4.31 

4.28 

4.24 

4. 21 

4.17 

4. 14 

4. 10 

4.07 

- 3 

4. 77 

4.73 

4.69 

4. 6 o 

4.61 

4.58 

4. 54 

4. .50 

4.46 

4. 42 

- 2 

5.18 

5. 14 

5.10 

5.06 

5. 01 

4.97 

4.93 

4.89 

4.85 

4.81 

- 1 

5.63 

5.58 

5.53 

5.49 

5.44 

5.40 

5. 36 

5.31 

5.27 

5.23 

- 0 

6.11 

6.06 

6. 01 

5.96 

5.91 

5.86 

5.81 

5. 77 

5.72 

5. 67 


0 

6.11 

6. 15 

6.20 

6.24 

6.29 

6.33 

6. 38 

6. 42 

6. 47 

6.52 

I 

6.56 

6.61 

6. 66 

6. 71 

6.76 

6. 81 

6.86 

6.90 

0. 95 

7.00 

2 

7.05 

7. 10 

7. 16 

7.21 

7.26 

7.31 

7.36 

7.42 

7.47 

7.52 

3 

7.58 

7.63 

7. 68 

7.74 

7.79 

7.85 

7.90 

7.96 

8.02 

8. 07 

4 

8.13 

8.19 

8.25 

8.30 

8.36 

8.42 

8.48 

8.54 

8.60 

8.66 

5 

8. 72 

8.78 

8.84 

8. 91 

8. 97 

9.03 

9.09 

9. 16 

9.22 

9.28 

6 

9. 35 

9.41 

9.48 

9.54 

9.61 

9.68 

9.74 

9. 81 

9. ,88 

9.95 

7 

10.02 

10.09 

10. 16 

10.22 

10.30 

10.37 

10.44 

10. 51 

10. 58 

10. 65 

8 

10.73 

10.80 

10. 87 

10.95 

11.02 

11. 10 

11. 17 

11.25 

11. 32 

11.40 

9 

11.48 

11.56 

11. 64 

11.71 

11.79 

11. 87 

11. 95 

12.03 

12.12 

12. 20 

10 

12.28 

12.36 

12.44 

12. ,53 

12.61 

12.70 

12. 78 

12. 87 

12. 95 

13. 04 

11 

13. 13 

13. 21 

13.30 

13. 39 

13. 48 

13. 57 

13.66 

13.75 

13. 84 

13. 93 

12 

14. 03 

14. 12 

14. 21 

14.31 

14. 40 

14.50 

14. 59 

14. 09 

14. 78 

14.88 

13 

14. 98 

15.08 

15. 18 

15. 28 

1.5. 38 

15. 48 

15. ,58 

15. OS 

15.78 

15.89 

14 

15. 99 

16.09 

16.20 

16. 30 

16.41 

16. 51 

16. 62 

16.73 

16. ,84 

10. 95 

IS 

17.06 

17. 17 

17.28 

17.39 

17. 50 

17.61 

17. 73 

17.84 

17.90 

18.07 

16 

18. 19 

18.30 

18.42 

18. ,54 

18. 66 

18.78 

18. 90 

19. 02 

19. 14 

19.26 

17 

19.38 

19.51 

19. 63 

19. 76 

19.88 

20.01 

20. 13 

20. 26 

20. 39 

20. 52 

18 

20. 65 

20. 78 

20.91 

21. 01 

21. 17 

21.31 

21. 11 

21. 5,8 

21.71 

21.85 

19 

21.98 

22.12 

22. 26 

22. 40 

22. 54 

22.68 

22. 82 

22. 96 

23. 11 

23. 25 

20 

23. 40 

23. 54 

23. 69 

23.83 

23.98 

24. 13 

24. 28 

24. 43 

2-1. 58 

24. 73 

21 

24.88 

25. 01 

25. 19 

25. 35 

25. 50 

25. 66 

2.5. 82 

2.5. 98 

26. 14 

26. 30 

22 

26. 46 

26. 62 

26. 78 

26. 94 

27. 11 

27. 27 

27. 41 

27.61 

27. 78 

27. 94 

23 

28. 11 

2. S . 28 

28. 46 

28. 63 

28.80 

2,8.98 ■ 

29.15 

29. 33 

29. 51 

29. 68 

24 

29.86 

30. 04 

30. 22 

30.40 

30. 59 

30.77 

30.96 

31. 14 

31.33 

31.51 

2 S 

31.70 

31. 89 

32. 08 

32.28 

32. 47 

32. 66 

32.86 

33. 05 

33.25 

33. 45 

26 

33. 64 

33. 84 

34. 04 

31. 25 

34. 45 

34. 05 

34. ,86 

35.06 

35. 27 

35. 48 

27 

35. 69 

35. 90 

: U ). 1 1 

36. 32 

36. 53 

36. 75 

30. 96 

37. 18 

37. 40 

37. 62 

28 

37. 84 

38. 06 

38. 28 

38. .50 

38. 73 

38. 95 

39. 18 

39.41 

.39. 64 

39. 87 

29 

40. 10 

40. 33 

40. .56 

40.80 

41.04 

41.27 

41.51 

41.75 

41.99 

42. 23 

30 

42. 48 

42. 72 

42. 97 

43. 21 

43. 46 

43.71 

43. 96 

41.21 

44. 47 

44. 72 

31 

44.98 

45. 23 

45. 49 

45. 75 

46.01 

46. 27 

46. 54 

40.80 

47. (17 

47. 33 

32 

47. 60 

47. 87 

48. 14 

48. 42 

48. 69 

48. 97 

49. 24 

49. 52 

49. SO 

50. 0.8 

33 

.50. 36 

,50. 65 

,50. 93 

51.22 

51. 50 

51.79 

52. 08 

52. 37 

52. 07 

52.96 

34 

53. 26 

.53. .56 

5.3. 85 

54. 15 

54. 46 

54.76 

55.06 

5,5. 37 

55. OS 

55. 99 

35 

56. 30 

.56.61 

.56. 92 

57. 24 

57.56 

57. 87 

.5,8. 19 

58. 51 

58. 84 

,59. 16 

36 

59.49 

.59. 81 

60. 14 

60. 47 

60. 81 

01. 11 

61.47 

01.81 

62. 15 

02. 49 

37 

62.83 

63. 17 

63. 52 

63. 86 

61.21 

61. ,56 

64.91 

65. 27 

65. 62 

65. 98 

38 

66. 34 

66. 69 

67. 06 

67. 42 

67. 78 

6,8. 15 

08. 52 

68, 89 

69. 26 

69. 03 

39 

70. 01 

70.38 

70.76 

71.14 

71.53 

71.91 

72. 30 

72. 08 

73.07 

73. 46 

40 

7.3.86 

74. 25 

74. 65 

7.5. 04 

75. 44 

7.5. ,85 

76. 25 

70. 60 

77. 06 

77. 47 

41 

77.88 

78. 30 

78.71 

79. 13 

79. 55 

79. 97 

,80. 39 

HO . 81 

81. 24 

81.67 

42 

82. 10 

82. 53 

82. 97 

as . 40 

S 3. 84 

8-1. 2,8 

84. 72 

8,5. 17 

8.5.61 

86. ( K 1 

43 

86. 51 

86.96 

87. 42 

87.87 

88. 33 

88. 79 

.89. 26 

89. 72 

90. 19 

«). 60 

44 

91.33 

91.60 

92. 07 

92. .55 

93.03 

93. 51 

93. 99 

91.48 

91.97 ■ 

95. 46 


INSTRUCTIONS FOR AEROLOOICAL OBSERVERS 


51 


Taulk 18 . — Relative humidity, per cent— centigrade temperatures. 

[ Pressure -U'.M) mb,] 


Depression of wet-bulb tberinometer (t-f). 


ature tO. 

.1 

2 

.3 

.4 

.5 

.6 

.7 

.8 

.9 

1.0 

t.l 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

2.2 

2.3 

2.4 

2.5 

2.0 

2.7 

2.8 

2.9 

3.0 

0 

98 

IM) 

94 

93 

91 

.89 

87 

85 

S3 

81 

80 

78 

70 

74 

73 

71 

09 

(57 

00 

04 

62 

00 

59 

57 

55 

53 

52 

50 

48 

40 

1 

98 

97 

9,5 

93 

92 

90 

88 

so 

85 

83 

81 

80 

78 

70 

75 

73 

71 

70 

08 

06 

04 

03 

01 

59 

58 

5(i 

54 

53 

51 

49 

2 

98 

97 

9,5 

93 

92 

90 

,89 

87 

85 

84 

82 

81 

7i) 

78 

70 

74 

73 

71 

70 

08 

67 

65 

63 

02 

00 

.59 

57 

.55 

.54 

.52 

3 

9S 

97 

95 

94 

92 

91 

89 

88 

86 

84 

83 

82 

80 

78 

77 

70 

74 

72 

71 

70 

68 

67 

65 

64 

02 

01 

.59 

58 

.56 

55 

4 

99 

97 

96 

94 

93 

91 

90 

88 

87 

85 

84 

82 

81 

79 

78 

77 

75 

74 

72 

71 

09 

68 

67 

65 

64 

02 

61 

00 

58 

57 

5 

99 

97 

96 

94 

93 

91 

90 

88 

87 

86 

84 

83 

82 

80 

79 

77 

76 

75 

73 

72 

71 

69 

68 

67 

05 

04 

62 

01 

60 

58 

6 

99 

97 

96 

94 

93 

92 

90 

89 

88 

86 

85 

,84 

82 

81 

80 

78 

77 

76 

74 

73 

72 

70 

69 

68 

07 

65 

04 

63 

01 

60 

7 

99 

97 

96 

95 

93 

92 

91 

89 

88 

87 

86 

84 

83 

82 

80 

79 

78 

77 

75 

74 

73 

72 

70 

69 

68 

67 

65 

H4 

63 

62 

8 

99 

97 

96 

95 

94 

92 

91 

90 

88 

87 

86 

85 

84 

82 

81 

80 

79 

77 

76 

75 

74 

73 

71 

70 

09 

68 

67 

65 

64 

63 

9 

99 

98 

96 

95 

91 

93 

91 

90 

89 

88 

87 

85 

84 

83 

82 

81 

79 

78 

77 

76 

75 

74 

72 

71 

70 

69 

68 

07 

06 

64 

10 

99 

98 

96 

95 

94 

93 

91 

90 

89 

88 

87 

80 

84 

83 

82 

81 

80 

79 

78 

77 

70 

74 

73 

72 

71 

70 

69 

68 

67 

66 

11 

99 

98 

97 

95 

94 

93 

92 

91 

90 

89 

87 

86 

85 

84 

83 

82 

81 

80 

79 

78 

70 

75 

74 

73 

72 

71 

70 

69 

68 

67 

12 

99 

98 

97 

96 

91 

93 

92 

91 

90 

89 

88 

87 

86 

85 

84 

82 

81 

80 

79 

78 

77 

76 

75 

74 

73 

72 

71 

70 

69 

08 

13 

99 

98 

97 

96 

95 

93 

92 

91 

90 

89 

88 

87 

86 

85 

84 

83 

82 

81 

80 

79 

78 

77 

76 

75 

74 

73 

72 

71 

70 

09 

14 

99 

98 

97 

96 

95 

94 

93 

92 

91 

90 

89 

88 

87 

80 

85 

84 

83 

82 

81 

79 

79 

78 

77 

76 

75 

74 

73 

72 

71 

70 


99 

98 

97 

96 

95 

94 

93 

92 

91 

90 

89 

88 

87 

86 

85 

84 

83 

82 

81 

80 

79 

78 

77 

76 

75 

74 

74 

73 

72 

71 

16 

99 

98 

97 

96 

95 

94 

93 

92 

91 

90 

89 

88 

87 

86 

85 

84 

83 

82 

82 

81 

80 

79 

78 

77 

70 

75 

74 

73 

72 

71 

17 

99 

98 

97 

90 

95 

94 

93 

92 

91 

90 

89 

89 

88 

87 

86 

85 

84 

83 

82 

81 

80 

79 

78 

78 

76 

75 

74 

73 

72 

72 

18 

99 

98 

97 

96 

95 

94 

93 

92 

92 

91 

90 

89 

88 

87 

80 

85 

84 

83 

83 

82 

81 

80 

79 

78 

77 

76 

76 

75 

74 

73 

19 

99 

98 

97 

96 

95 

95 

94 

93 

92 

91 

90 

89 

88 

87 

87 

86 

85 

84 

83 

82 

81 

80 

80 

79 

78 

77 

76 

75 

75 

74 

20 

99 

98 

97 

96 

96 

95 

94 

93 

92 

91 

90 

89 

89 

88 

87 

86 

85 

84 

83 

83 

82 

81 

SO 

79 

78 

78 

77 

76 

75 

74 

21 

99 

98 

97 

97 

96 

95 

94 

93 

92 

91 

90 

90 

89 

88 

87 

86 

84 

85 

84 

83 

82 

81 

81 

80 

79 

78 

77 

77 

70 

75 

22 

99 

98 

97 

97 

96 

95 

94 

93 

92 

92 

91 

90 

89 

88 

87 

87 

86 

85 

84 

S3 

83 

82 

81 

80 

80 

79 

78 

77 

76 

76 

23 

99 

98 

97 

97 

96 

95 

94 

93 

93 

92 

91 

90 

89 

89 

88 

87 

86 

85 

85 

84 

S3 

82 

81 

81 

80 

79 

78 

78 

77 

76 

24 

99 

98 

98 

97 

96 

95 

94 

94 

93 

92 

91 

90 

90 

89 

88 

87 

87 

86 

85 

84 

83 

83 

82 

81 

80 

80 

79 

78 

77 

77 

25 

99 

98 

98 

97 

96 

95 

94 

94 

93 

92 

91 

91 

90 

89 

88 

88 

87 

86 

85 

84 

84 

83 

82 

82 

81 

80 

79 

79 

78 

77 

26 

99 

98 

98 

97 

96 

95 

95 

94 

93 

92 

91 

91 

90 

89 

88 

88 

87 

86 

86 

85 

84 

83 

83 

82 

81 

80 

80 

79 

78 

78 

27 

99 

98 

98 

97 

96 

95 

95 

94 

93 

92 

92 

91 

90 

89 

89 

88 

87 

87 

86 

85 

84 

84 

83 

82 

82 

81 

80 

79 

79 

78 

28 

99 

99 

98 

97 

96 

96 

95 

94 

93 

93 

92 

91 

90 

90 

89 

88 

88 

87 

86 

85 

85 

84 

83 

S3 

S2 

81 

81 

80 

79 

78 

29 

99 

99 

98 

97 

96 

96 

95 

94 

93 

93 

92 

91 

90 

90 

89 

88 

88 

87 

86 

86 

85 

84 

84 

83 

82 

82 

81 

SO 

80 

79 

30 

99 

99 

98 

97 

96 

96 

95 

94 

94 

93 

92 

91 

91 

90 

89 

89 

88 

87 

87 

86 

85 

85 

84 

83 

83 

82 

81 

81 

80 

79 

31 

99 

99 

98 

97 

96 

96 

95 

94 

94 

93 

92 

92 

91 

90 

90 

89 

88 

87 

87 

86 

86 

85 

84 

84 

83 

82 

82 

81 

80 

80 

32 

99 

99 

98 

97 

90 

90 

95 

94 

94 

93 

92 

92 

91 

90 

90 

89 

88 

88 

87 

86 

86 

85 

84 

84 

83 

83 

S2 

81 

81 

80 

33 

99 

99 

98 

97 

97 

96 

95 

94 

94 

93 

92 

92 

91 

90 

90 

89 

89 

88 

87 

87 

86 

85 

85 

84 

83 

83 

82 

82 

81 

80 

34 

99 

99 

98 

97 

97 

96 

95 

95 

94 

93 

93 

92 

91 

91 

90 

89 

89 

88 

87 

87 

86 

86 

85 

84 

84 

83 

82 

82 

81 

81 

35 

99 

99 

98 

97 

97 

96 

95 

95 

94 

94 

93 

92 

91 

91 

90 

90 

89 

88 

88 

87 

86 

86 

85 

85 

84 

83 

S3 

82 

82 

81 

36 

99 

99 

98 

97 

97 

96 

95 

95 

94 

94 

93 

92 

92 

91 

90 

90 

89 

88 

88 

87 

87 

86 

85 

85 

84 

84 

83 

82 

82 

81 

37 

99 

99 

98 

97 

97 

90 

96 

95 

94 

94 

93 

92 

92 

91 

91 

90 

89 

89 

88 

87 

87 

86 

86 

85 

84 

84 

83 

83 

82 

82 

38 

99 

99 

98 

97 

97 

96 

96 

95 

94 

94 

93 

92 

92 

91 

91 

90 

89 

89 

88 

88 

87 

86 

86 

85 

84 

84 

84 

83 

82 

82 

39 

99 

99 

98 

98 

97 

96 

90 

95 

94 

94 

93 

93 

92 

91 

91 

90 

90 

89 

88 

88 

87 

87 

86 

86 

85 

84 

84 

83 

S3 

82 

40 

99 

99 

98 

98 

97 

90 

96 

95 

94 

94 

93 

93 

92 

91 

91 

90 

90 

89 

89 

88 

87 

87 

80 

86 

85 

85 

84 

84 

83 

82 

41 

99 

99 

98 

98 

97 

90 

90 

95 

95 

94 

93 

93 

92 

92 

91 

91 

90 

89 

89 

88 

88 

87 

87 

86 

85 

85 

84 

84 

S3 

83 

42 

99 

99 

98 

98 

97 

90 

90 

95 

95 

94 

93 

93 

92 

92 

91 

91 

90 

89 

89 

88 

88 

87 

87 

86 

86 

85 

84 

84 

83 

83 

43 

99 

99 

98 

98 

97 

90 

90 

95 

95 

94 

04 

93 

92 

92 

91 

91 

90 

90 

89 

88 

88 

87 

87 

86 

86 

S5 

85 

84 

84 

83 

44 

99 

99 

98 

98 

97 

97 

90 

95 

95 

94 

94 

93 

93 

92 

91 

91 

90 

90 

89 

89 

88 

88 

87 

86 

80 

85 

85 

84 

84 

83 


Air tem- 


Deprossion of wet-bulb thermometer (t—f). 


perature (f). 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

5.4 

5.5 

5.6 

5.7 

5.8 

5.9 

6.0 

0 

45 

43 

41 

40 

38 

30 

34 

33 

31 

29 

28 

26 

24 

23 

21 

20 

18 

16 

15 

13 

11 

10 

8 

7 

5 






1 

48 

40 

45 

43 

41 

40 

38 

36 

35 

33 

32 

30 

28 

27 

25 

24 

22 

21 

19 

17 

16 

14 

13 

11 

10 

8 

7 

5 



2 

51 

49 

48 

46 

44 

43 

41 

40 

38 

37 

35 

34 

32 

31 

29 

28 

26 

25 

23 

22 

20 

19 

17 

16 

14 

13 

11 

10 

8 

7 

3 

53 

52 

50 

49 

47 

46 

44 

43 

41 

40 

39 

37 

36 

34 

33 

31 

30 

28 

27 

20 

24 

23 

21 

20 

19 

17 

16 

14 

13 

12 

4 

5.5 

54 

.53 

51 

50 

48 

47 

46 

44 

43 

42 

40 

39 

37 

30 

35 

33 

32 

31 

29 

28 

26 

25 

24 

22 

21 

20 

18 

17 

16 

5 

57 

50 

54 

53 

52 

51 

49 

48 

47 

45 

44 

43 

42 

40 

39 

38 

37 

35 

34 

33 

31 

30 

29 

28 

26 

25 

24 

22 

21 

20 

0 

59 

58 

,50 

65 

54 

53 

51 

50 

49 

48 

40 

45 

41 

43 

41 

40 

39 

38 

37 

35 

34 

33 

32 

31 

29 

28 

27 

26 

25 

24 

7 

60 

59 

58 

57 

50 

.54 

53 

52 

51 

50 

48 

47 

46 

15 

41 

43 

41 

40 

39 

38 

37 

30 

34 

33 

32 

31 

30 

29 

28 

26 

8 

62 

01 

.59 

58 

57 

56 

55 

54 

52 

51 

.V) 

49 

48 

47 

46 

45 

44 

42 

41 

40 

39 

38 

37 

36 

35 

31 

32 

31 

30 

29 


03 

62 

01 

60 

59 

58 

56 

55 

54 

53 

52 

51 

50 

49 

48 

47 

46 

45 

43 

42 

41 

40 

39 

38 

37 

36 

35 

34 

33 

32 

10 

6.5 

03 

02 

61 

60 

.59 

58 

57 

56 

55 

.54 

53 

52 

51 

50 

49 

47 

40 

45 

44 

43* 

42 

41 

40 

39 

38 

37 

36 

35 

34 

11 

00 

6.5 

04 

02 

01 

(>0 

59 

58 

57 

.56 

55 

.5^1 

53 

52 

51 

59 

49 

48 

47 

40 

45 

41 

43 

42 

41 

40 

39 

38 

37 

36 

12 

07 

00 

05 

04 

63 

02 

61 

60 

59 

58 

57 

.58 

5.5 

54 

.53 

52 

51 

50 

49 

48 

47 

48 

45 

44 

43 

42 

41 

40 

40 

39 


68 

07 

66 

05 

04 

63 

02 

61 

00 

59 

58 

57 

56 

55 

54 

53 

52 

51 

51 

50 

49 

48 

47 

40 

45 

44 

43 

42 

42 

41 

14 

09 

68 

07 

00 

65 

04 

63 

62 

61 

00 

.59 

58 

58 

57 

56 

55 

54 

53 

52 

51 

.50 

50 

49 

48 

47 

46 

45 

44 

43 

42 

15 

70 

09 

08 

07 

00 

05 

04 

63 

02 

61 

61 

00 

59 

58 

57 

56 

55 

54 

.54 

53 

52 

51 

50 

49 

48 

48 

47 

40 

4,5 

44 

10 

71 

70 

69 

08 

07 

00 

05 

04 

0.3 

03 

62 

61 

00 

.59 

58 

58 

57 

56 

55 

54 

.53 

52 

52 

51 

50 

49 

48 

47 

47 

40 

17 

71 

70 

70 

69 

68 

07 

66 

0.5 

04 

04 

(i:> 

02 

61 

60 

00 

59 

58 

57 

.50 

.55 

55 

54 

.53 

52 

51 

51 

50 

49 

48 

47 

18 

72 

71 

70 

70 

69 

68 

07 

66 

05 

65 

04 

03 

02 

61 

61 

60 

59 

58 

57 

57 

56 

.55 

54 

53 

.5;i 

52 

51 

50 

49 

49 

19 

73 

72 

71 

70 

70 

(i9 

68 

07 

06 

0.5 

05 

04 

03 

02 

02 

61 

60 

59 

58 

58 

57 

.56 

55 

55 

54 

53 

52 

52 

51 

50 

20 

71 

7.3 

72 

71 

70 

70 

0!) 

68 

07 

66 

66 

65 

64 

03 

03 

62 

01 

60 

.59 

.59 

58 

57 

,50 

56 

,55 

,54 

51 

.53 

52 

51 

21 

74 

73 

73 

72 

71 

70 

70 

09 

68 

67 

06 

00 

0.5 

01 

64 

0.3 

02 

61 

61 

00 

.59 

58 

58 

57 

,56 

55 

55 

54 

,53 

.53 

22 

75 

74 

73 

73 

72 

71 

70 

70 

09 

68 

67 

67 

60 

65 

61 

01 

03 

02 

61 

01 

00 

.59 

59 

58 

57 

,56 

.56 

.55 

51 

54 

23 

7.5 

7.5 

74 

73 

72 

72 

71 

70 

70 

69 

08 

07 

07 

00 

65 

64 

6-1 

6:i 

62 

02 

6! 

00 

00 

.59 

58 

58 

57 

,56 

55 

55 

21 

70 

75 

71 

74 

73 

72 

72 

71 

70 

69 

09 

68 

07 

07 

60 

05 

65 

04 

63 

02 

02 

01 

60 

60 

.59 

58 

,58 

57 

50 

.50 

25 

70 

70 

75 

74 

74 

73 

72 

72 

71 

70 

69 

09 

08 

67 

07 

00 

65 

65 

01 

63 

03 

02 

01 

01 

60 

.59 

.59 

68 

57 

57 

26 

77 

70 

70 

75 

74 

74 

73 

72 

71 

71 

70 

69 

09 

68 

07 

07 

66 

05 

05 

64 

03 

03 

02 

62 

01 

60 

60 

59 

58 

58 

27 

77 

77 

70 

75 

7.5 

71 

73 

73 

72 

71 

71 

70 

09 

09 

68 

07 

67 

60 

65 

05 

04 

04 

63 

02 

62 

61 

60 

60 

,59 

.58 

28 

78 

77 

77 

70 

7.5 

75 

74 

73 

73 

72 

71 

71 

70 

09 

(iO 

08 

67 

07 

r>6 

65 

65 

04 

04 

63 

62 

62 

61 

01 

60 

59 

29 

78 

78 

77 

70 

70 

75 

71 

74 

73 

72 

72 

71 

71 

70 

69 

09 

68 

67 

67 

60 

06 

05 

04 

64 

63 

62 

02 

61 

61 

00 

30 

79 

78 

77 

77 

70 

75 

75 

74 

74 

73 

72 

72 

71 

70 

70 

m 

09 

68 

07 

07 

66 

00 

05 

()4 

64 

03 

03 

62 

61 

01 

31 

79 

78 

78 

77 

77 

70 

75 

74 

74 

73 

73 

72 

72 

71 

70 

70 

09 

69 

68 

07 

07 

66 

66 

05 

64 

04 

6:{ 

68 

62 

01 

32 

79 

70 

78 

78 

77 

70 

70 

7.5 

75 

74 

73 

73 

72 

72 

71 

70 

70 

69 

68 

68 

07 

67 

041 

06 

05 


04 

63 

03 

62 


80 

79 

78 

78 

77 

77 

70 

70 

7,5 

71 

71 

73 

73 

72 

71 

71 

70 

70 

69 

68 

68 

67 

07 

66 

66 

65 

65 

64 

03 

63 

34 

SO 

79 

79 

78 

78 

77 

70 

70 

75 

75 

74 

74 

73 

72 

72 

71 

71 

70 

70 

09 

68 

08 

07 

67 

66 

66 

05 

65 

04 

63 


HO 

80 

79 

79 

78 

77 

77 

70 

70 

7.5 

7.5 

71 

73 

73 

72 

72 

71 

71 

70 

09 

09 

08 

08 

07 

67 

60 

06 

05 

65 

64 

30 

81 

80 

79 

79 

78 

78 

77 

77 

70 

7,5 

7.5 

74 

74 

73 

7:i 

72 

72 

71 

70 

70 

09 

09 

68 

68 

67 

00 

66 

65 

65 

64 

37 

81 

80 

80 

79 

79 

78 

78 

77 

76 

70 

7.5 

75 

74 

71 

73 

73 

72 

72 

71 

70 

70 

09 

09 

68 

68 

67 

67 

66 

66 

65 

38 

81 

81 

80 

80 

79 

78 

78 

77 

77 

70 

70 

75 

75 

74 

74 

73 

72 

72 

71 

71 

70 

70 

09 

69 

68 

68 

07 

67 

66 

66 


82 

81 

80 

80 

79 

79 

78 

77 

77 

77 

76 

76 

75 

74 

74 

73 

73 

72 

72 

71 

71 

70 

70 

69 

69 

68 

68 

67 

67 

06 

40 

82 

81 

81 

80 

80 

79 

79 

78 

77 

77 

70 

70 

75 

75 

71 

74 

73 

73 

72 

72 

71 

71 

70 

70 

69 

09 

08 

68 

67 

67 

41 

82 

82 

81 

80 

80 

79 

79 

78 

78 

77 

77 

70 

70 

75 

75 

74 

74 

73 

73 

72 

72 

71 

71 

70 

70 

09 

69 

68 

08 

67 

42 

82 

82 

81 

81 

80 

80 

79 

79 

78 

78 

77 

70 

70 

75 

75 

74 

74 

7,3 

73 

72 

72 

71 

71 

70 

70 

09 

69 

68 

68 

07 

43 

82 

82 

81 

81 

80 

80 

79 

79 

78 

78 

77 

77 

70 

70 

75 

75 

71 

74 

73 

73 

72 

72 

71 

71 

70 

70 

09 

69 

08 

08 

44 

83 

82 

82 

81 

81 

80 

80 

79 

79 

78 

78 

77 

77 

70 

76 

75 

75 

74 

74 

73 

73 

72 

72 

71 

71 

70 j 

70 

69 

69 

68 


52 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 

Table 18. — Relative humidity, per cent — centigrade temperatures — Continued. 


Depression of wet-bulb thermometer 


turc (t). 

6.1 

6.2 

6.3 

6.4 

0.5 

6.6 

6.7 

6.8 

6.9 

7.0 

7.1 

7.2 

7.3 

7.4 

7.5 

7.6 

7.7 

7.8 

7.9 

8.0 

8.1 

8.2 

8.3 

8.4 

8.5 

8.6 

8.7 

8.8 

8.9 

9.0 

2 

3 

6 

10 

9 

8 

6 

5 


























4 

14 

13 

12 

11 

9 

8 

7 

5 























5 

18 

17 

16 

15 

13 

12 

11 

10 

8 

7 

6 

5 



















6 

22 

21 

20 

19 

17 

16 

15 

14 

13 

11 

10 

9 

8 

6 

5 
















7 

25 

24 

23 

22 

21 

20 

19 

18 

17 

15 

14 

13 

12 

11 

10 

9 

8 

7 

5 












8 

28 

27 

26 

25 

24 

23 

22 

21 

20 

19 

IS 

17 

16 

15 

14 

12 

11 

10 

9 

8 

7 

6 

5 








9 

31 

30 

29 

28 

27 

26 

25 

24 

23 

22 

21 

20 

19 

18 

17 

16 

15 

14 

13 

12 

11 

10 

9 

8 

7 

6 

5 




10 

33 

32 

31 

30 

29 

28 

27 

26 

25 

24 

23 

22 

22 

21 

20 

19 

18 

17 

16 

15 

14 

13 

12 

11 

10 

9 

8 

7 

7 

6 

11 

35 

35 

34 

33 

32 

31 

30 

29 

28 

27 

26 

25 

24 

23 

22 

22 

21 

20 

19 

18 

17 

16 

15 

14 

13 

13 

12 

11 

10 

9 

12 

38 

37 

36 

35 

34 

33 

32 

31 

30 

29 

29 

28 

27 

26 

25 

24 

23 

22 

22 

21 

20 

19 

18 

17 

16 

16 

15 

14 

13 

12 

13 

40 

39 

38 

37 

36 

35 

34 

34 

33 

32 

31 

30 

29 

28 

28 

27 

26 

25 

24 

23 

22 

22 

21 

20 

19 

18 

17 

17 

16 

15 

14 

42 

41 

40 

39 

38 

37 

36 

36 

35 

34 

33 

32 

31 

31 

30 

29 

28 

27 

27 

26 

25 

24 

23 

22 

22 

21 

20 

19 

18 

18 

15 

43 

43 

42 

41 

40 

39 

38 

38 

37 

30 

35 

34 

33 

32 

32 

31 

30 

29 

28 

27 

27 

26 

25 

24 

24 

23 

22 

22 

21 

20 

16 

45 

44 

43 

43 

42 

41 

40 

39 

39 

38 

37 

36 

35 

35 

31 

33 

32 

32 

31 

30 

29 

29 

28 

27 

26 

26 

25 

24 

23 

23 

17 

47 

46 

45 

44 

43 

43 

42 

41 

40 

40 

39 

38 

37 

37 

36 

35 

34 

34 

33 

32 

31 

31 

30 

29 

28 

28 

27 

26 

26 

25 

IS 

48 

47 

46 

46 

45 

44 

43 

43 

42 

41 

40 

40 

39 

38 

38 

37 

36 

35 

35 

34 

33 

33 

32 

31 

30 

30 

29 

28 

28 

27 

19 

49 

49 

48 

47 

46 

46 

45 

44 

4-1 

43 

42 

41 

40 

40 

39 

39 

38 

37 

38 

36 

35 

34 

34 

33 

32 

32 

31 

30 

30 

29 

20 

51 

50 

49 

48 

48 

47 

46 

46 

45 

44 

44 

43 

42 

41 

41 

40 

39 

39 

38 

37 

37 

36 

35 

35 

34 

33 

33 

32 

31 

31 

21 

52 

51 

50 

50 

49 

48 

48 

47 

46 

46 

45 

44 

44 

43 

42 

42 

41 

40 

40 

39 

38 

38 

37 

36 

36 

35 

34 

34 

33 

32 

22 

53 

52 

52 

51 

50 

50 

49 

48 

48 

47 

46 

46 

45 

44 

44 

43 

42 

42 

41 

40 

40 

39 

39 

3S 

37 

37 

36 

35 

35 

34 

23 

54 

.53 

53 

52 

52 

51 

50 

50 

49 

48 

43 

47 

46 

46 

45 

44 

44 

43 

42 

42 

41 

41 

40 

39 

39 

3S 

38 

37 

26 

36 

24 

55 

54 

54 

53 

53 

52 

51 

51 

50 

49 

49 

48 

47 

47 

46 

46 

45 

44 

44 

43 

43 

42 

41 

41 

40 

40 

39 

38 

38 

37 

25 

56 

55 

55 

54 

54 

53 

52 

52 

51 

50 

50 

49 

49 

48 

47 

47 

46 

46 

45 

44 

44 

43 

43 

42 

41 

41 

40 

40 

39 

39 

26 

57 

56 

56 

55 

54 

54 

53 

53 

52 

51 

51 

50 

50 

49 

49 

48 

47 

47 

46 

46 

45 

44 

44 

43 

43 

42 

42 

41 

40 

40 

27 

58 

57 

57 

56 

56 

55 

54 

54 

53 

52 

52 

51 

51 

50 

50 

49 

48 

48 

47 

47 

46 

46 

45 

44 

44 

43 

43 

42 

42 

41 

28 

59 

58 

58 

57 

56 


55 


5t 

53 

53 

52 

52 

51 

51 

50 

49 

49 

48 

48 

47 

47 

46 

46 


44 

44 

43 

43 

42 

29 

60 

59 

58 

58 

57 

57 

56 

55 

55 

54 

54 

53 

53 

52 

52 

51 

50 

50 

49 

49 

48 

48 

47 

47 

46 

46 

45 

44 

44 

43 

30 

60 

60 

59 

59 

58 

57 

57 

56 

56 

55 

55 

54 

53 

53 

52 

52 

51 

51 

50 

• 50 

49 

49 

48 

48 

47 

47 

46 

45 

45 

44 

31 

61 

60 

60 

59 

59 

58 

58 

57 

57 

56 

55 

55 

54 

54 

53 

53 

52 

52 

51 

51 

50 

50 

49 

49 

48 

48 

47 

47 

46 

45 

32 

62 

61 

61 

60 

60 

59 

58 

58 

57 

57 

56 

56 

55 

55 

51 

54 

53 

52 

52 

51 

51 

50 

50 

49 

49 

48 

48 

47 

47 

46 

33 

62 

62 

61 

61 

60 

60 

59 

59 

58 

57 

57 

56 

56 

55 

55 

54 

54 

53 

53 

52 

52 

51 

51 

50 

50 

49 

49 

48 

48 

47 

34 

63 

62 

62 

61 

61 

60 

60 

59 

59 

58 

58 

57 

Ot 

56 

56 

55 

55 

54 

54 

53 

53 

52 

52 

51 

51 

50 

50 

49 

49 

48 

35 

64 

63 

63 

62 

61 

01 

60 

60 

59 

59 

58 

58 

57 

57 

56 

56 

55 

54 

54 

5i 

53 

53 

52 

52 

51 

51 

50 

50 

49 

49 

36 

64 

63 

63 

62 

62 

61 

61 

60 

60 

59 

59 

58 

58 

57 

57 

56 

56 

55 

55 

54 

54 

53 

53 

53 

52 

52 

51 

51 

50 

50 

37 

65 

64 

04 

63 

63 

62 

62 

61 

61 

60 

00 

59 

59 

58 

58 

57 

57 

56 

56 

55 

55 

54 

54 

53 

53 

52 

52 

51 

51 

51 

38 

65 

65 

64 

61 

63 

63 

62 

62 

61 

61 

60 

60 

59 

59 

58 

58 

57 

57 

56 

56 

55 

55 

55 

54 

54 

53 

53 

52 

52 

51 

39 

66 

65 

65 

64 

64 

63 

63 

62 

02 

61 

61 

60 

60 

59 

59 

58 

58 

57 

57 

57 

56 

56 

55 

55 

54 

54 

53 

53 

52 

62 

40 

66 

66 

65 

65 

64 

64 

63 

63 

62 

52 

61 

61 

60 

60 

59 

59 

59 

58 

58 

57 

57 

56 

56 

55 

54 

54 

54 

54 

53 

53 

41 

67 

68 

66 

65 

65 

64 

64 

63 

63 

62 

62 

61 

61 

60 

60 

60 

59 

59 

58 

58 

57 

57 

.56 

56 

56 

55 

55 

54 

51 

53 

42 

67 

67 

66 

66 

05 

05 

64 

64 

63 

63 

62 

62 

61 

61 

61 

60 

60 

59 

59 

58 

58 

57 

57 

57 

56 

56 

55 

54 

54 

54 

43 

67 

67 

66 

66 

66 

65 

65 

64 

64 

63 

63 

62 

62 

61 

61 

61 

60 

60 

59 

59 

58 

58 

58 

57 

57 

56 

56 

55 

55 

55 

44 

68 

67 

67 

66 

6o 

66 

65 

65 

64 

01 

63 

63 

62 

62 

62 

61 

61 

60 

60 

59 

59 

58 

58 

58 

57 

57 

56 

56 

56 

55 


Depression of wet-bulb thermometer tf—t'). 


xemijeraiure 

(0. 

9.1 

9.2 

9.3 

9.4 

9.5 

9.6 

9.7 

9.8 

9.9 

10.0 

10.1 

10.2 

10. .S 

10.4 

10.5 

10.6 

10.7 

10.8 

10.9 

11.0 

11.1 

11.2 

11.3 

11.4 

11.5 

11.6 

11.7 

11.8 

11.9 

12.0 

10 

5 






























11 

8 

7 

6 

6 

5 


























12 

11 

10 

10 

9 

8 

7 

6 

5 

5 






















13 

14 

13 

13 

12 

11 

10 

9 

9 

8 

7 

G 

0 



















14 

17 

16 


15 

14 

13 

12 

11 

11 

10 

9 

8 

8 

7 

6 

6 

5 














15 

20 

19 

18 

17 

10 

16* 

18 

15 

14 

13 

13 

12 

11 

11 

10 

9 

8 

8 

7 

6 

6 











16 

22 

21 

20 

20 

19 

17 

17 

16 

1.5 

15 

14 

13 

13 

12 

11 

10 

10 

9 

8 

8 

7 

6 

6 

5 






17 

24 

23 

23 

22 

21 

21 

20 

19 

18 

18 

17 

16 

16 

1.5 

14 

14 

13 

12 

12 

11 

10 

10 

9 

8 

8 

7 

6 

6 

5 


18 

26 

26 

25 

24 

23 

23 

22 

21 

21 

20 

19 

19 

18 

17 

17 

16 

15 

15 

14 

14 

13 

12 

12 

11 

10 

10 

9 

8 

8 

7 

19 

28 

28 

27 

20 

20 

25 

24 

24 

23 

22 

22 

21 

20 

20 

19 

18 

18 

17 

17 

10 

15 

15 

14 

13 

13 

12 

12 

11 

10 

10 

20 

30 

29 

20 

28 

28 

27 

26 

26 

2.5 

2-i 

24 

23 

22 

22 

21 

21 

20 

19 

19 

18 

18 

17 

16 

16 

1.5 

15 

u 

13 

13 

12 

21 

32 

31 

31 

30 

29 

29 

28 

28 

27 

20 

26 

25 

24 

24 

23 

23 

22 

22 

21 

20 

20 

19 

19 

18 

17 

17 

16 

16 

15 

14 

22 

3-1 

33 

32 

32 

31 

30 

30 

29 

29 

28 

28 

27 

26 

2() 

25 

25 

2-1 

23 

23 

22 

22 

21 

20 

20 

19 

19 

IS 

IS 

17 

17 

23 

3.5 

34 

34 

23 

33 

32 

32 

31 

30 

30 

29 

29 

28 

27 

27 

2(> 

26 

2.5 

25 

24 

24 

23 

22 

22 

21 

21 

20 

20 

19 

19 

24 

37 

36 

35 

35 

34 

34 

33 

33 

32 

31 

31 

30 

30 

29 

29 

28 

27 

27 

2() 

26 

25 

25 

21 

24 

23 

23 

22 

21 

21 

20 

25 

38 

37 

.37 

36 

36 

35 

35 

34 

33 

33 

32 

32 

31 

31 

30 

30 

29 

29 

28 

28 

27 

26 

26 

2.5 

2.5 

24 

24 

23 

23 

22 


39 

39 

38 

38 

37 

37 

36 

35 

3.5 

34 

34 

33 

33 

32 

32 

31 

31 

30 

30 

29 

28 

28 

27 

27 

26 

26 

2.5 

2.5 

24 

24 

27 

41 

40 

3il 

39 

38 

38 

37 

37 

36 

36 

35 

35 

34 

34 

35 

33 

33 

32 

32 

31 

31 

30 

30 

29 

29 

28 

2S 

27 

27 

26 

26 

28 

42 

41 

41 

40 

40 

39 

39 

38 

38 

37 

36 

36 

35 

34 

34 

33 

33 

32 

32 

31 

31 

30 

30 

29 

29 

28 

28 

27 

27 

2<1 

43 

42 

42 

41 

41 

40 

40 

39 

39 

38 

38 

37 

37 


30 

35 

35 

34 

35 

31 

33 

33 

32 

32 

31 

31 

30 

30 

» 

29 

28 

30 

44 

43 

13 

42 

42 

41 

41 

40 

40 

30 

39 

38 

.38 

37 

37 

36) 

36 

35 

3.5 

34 

34 

35 

33 

33 

32 

33 

32 

31 

31 

30 

30 

31 

45 

41 

44 

43 

44 

43 

42 

42 

41 

‘12 

41 

42 

40 

40 

<11 

40 

4-1 

39 

40 

39 

40 

38 

3S 

39 

87 

37 

36 

36 

35 

36 

34 

34 

3.5 

33 

32 

32 

32 

31 

39 

45 

46 

43 

44 

43 

44 

39 

40 

38 

39 

40 

38 

39 

37 

38 

39 

.37 

38 

36 

36 

36 

35 

36 

34 

35 

34 

35 

33 

33 

32 

.33 

47 

48 

46 

47 

45 

^5 

43 

43 

44 

42 

43 

42 

43 

42 

41 

41 

40 

37 

37 

36 

34 

35 

34 

33 

34 

47 

4fi 

46 

45 

45 

^4 

43 

42 

42 

41 

41 

40 

39 

39 

38 

38 

37 

37 

36 

36 

35 

35 

3.5 

49 

49 

48 

48 

47 

48 

47 

Afi 

46 

46 

45 

4C 

45 

44 

44 

44 

‘U 

43 

43 

42 

43 

42 

43 

41 

'12 

41 

‘12 

40 

‘U 

40 

‘U 

40 

40 

39 

3i> 

38 

3S 

37 

37 

37 

.36 

36 


49 

.50 

47 

48 

47 

47 


40 

41 

40 

41 

39 

40 

39 

40 

3S 

39 

3S 

39 

38 

38 

37 

37 

37 

.50 

49 

49 

48 

47 

47 

4f) 

46 

45 

45 

44 

44 

4.) 

44 

43 

43 

12 

42 

41 

38 

38 

38 

.51 

50 

50 

50 

49 

49 

48 

48 

47 

47 

4() 


16 

45 

44 

44 

44 

43 

43 

42 

42 

41 

41 

41 

40 

40 

39 

39 

39 

39 

52 

51 

51 

50 

50 

49 

49 

4S 

48 

48 

47 

47 

16 

46 

46 

45 

45 

44 

44 

43 

43 

43 

42 

42 

42 

41 

41 

40 

40 

39 

40 

52 

52 

51 

51 

51 

50 

50 

49 

49 

48 

4.S 

48 

47 

47 

4f) 

46 

46) 

'1.5 

4.5 

44 

4.5 

44 

44 

43 

43 

42 

42 

42 

41 

40 

40 

41 

53 

52 

52 

52 

51 

.51 

50 

50 

.50 

49 

49 

48 

48 

47 

47 

47 

46 

46 

45 

4.5 

44 

44 

43 

43 

43 

42 

42 

41 

41 

42 


53 

54 
54 

5.3 

53 

.54 

52 
5.3 

53 

52 

52 

5.3 

51 

51 

.51 

50 

51 
51 

50 

50 

51 

49 

50 

51 

40 

50 

50 

48 

48 

49 
49 

4S 

48 

49 

47 

47 

48 
48 

46 

46 

46 

45 

4.5 


41 

44 

43 

43 

43 

42 

42 

43 

44 

54 

55 

52 

53 

52 

52 

.51 

52 

49 

50 

4S 

49 

47 

48 

47 

17 

4i; 

47 

46 

47 

46 

46 

45 

46 

4.5 

46 

44 

4.5 

44 

45 

44 

44 

43 

44 

43 

44 

43 

43 


INiSTRlK’TlONS FOR AFROLOGICAL OJFSERVERS, 


53 



INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 

Table 18. — Relative humidity, per cent — centigrade temperatures— Continued. 


r)4 


Depression of wet-bulb thermometer (< — t'). 


Air tcmpora- 


ture (t). 

21.1 

21.2 

21.3 

21.4 

21.5 1 

21.6 

21.7 

21.8 

21.9 

22.0 

22.1 

22.2 

22.3 

22.4 

22.5 

22.6 

22.7 

22.8 

22.9 

23.0 

23.1 

23.2 

23.3 

23.4 

23.5 

23.6 

23.7 

23.8 

23.9 

24.0 

36 

5 

5 





























37 

7 

6 

6 

6 

5 

5 

5 

5 























38 

8 

8 

8 

7 

7 

7 

6 

6 

6 

5 

5 

5 

5 


















39 

9 

9 

9 

8 

8 

8 

8 

7 

7 

7 

7 

6 

6 

6 

6 

5 

5 

5 













40 

11 

10 

10 

10 

10 

9 

9 

9 

8 

8 

8 

8 

7 

7 

7 

7 

6 

6 

6* 

6 

5 

5 

5 

5 







41 

12 

12 

11 

11 

11 

10 

10 

10 

10 

9 

9 

9 

9 

8 

8 

8 

8 

7 

7 

7 

7 

6 

6 

6 

6 

5 

5 

5 

5 


42 

13 

13 

13 

12 

12 

12 

11 

11 

11 

11 

10 

10 

10 

10 

9 

9 

9 

9 

8 

8 

8 

8 

7 

7 

7 

7 

6 

6 

6 

6 

43 

14 

14 

14 

13 

13 1 

13 

13 

12 

12 

12 

11 

11 

11 

11 

11 

10 

10 

10 

10 

9 

9 

9 

9 

8 

8 

8 

8 

7 

7 

i 

44 

15 

15 

15 

15 

14 1 

14 

14 

13 

13 

13 

13 

12 

12 

12 

12 

11 

11 

11 

11 

10 

10 

10 

10 

10 

9 

9 

9 

9 

8 

8 












Depression of wet-bulb thermometer (< 

-t'). 












Air tempera- 































true (t). 































• 

24.1 

24.2 

24.3 

24.4 

24.5 

24.6 

24.7 

24.8 

24.9 

25.0 

25.1 

25.2 

25.3 

25.4 

25.5 

25.6 















42 

5 

5 

5 

5 

5 


























43 

7 

7 

6 

6 

6 

6 

5 

5 

5 

5 





















44 

8 

8 

7 

7 

7 

7 

7 

6 

6 

6 

6 

5 

5 

5 

5 

5 



























Depression of wet-bulb thermometer (f— ('). 












Air tempera- 































ture (i). 
































0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

1. 1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2. 1 

2.2 

2.3 

2.4 

2.5 

2.0 

2.7 

2.8 

2.9 

3.0 

—39 

5fi 

11 





























-38 

60 

21 





























-37 

64 

28 





























-36 

68 

36 





























-35 

71 

42 

13 




























-34 

74 

48 

22 




























-33 

77 

53 

30 

6 



























-32 

79 

57 

36 

15 



























-31 

81 

62 

42 

23 



























-30 

83 

65 

48 

30 

13 


























-29 

84 

68 

53 

37 

21 

5 

























-28 

86 

71 

57 

43 

28 

14 

























-27 

87 

74 

61 

48 

35 

22 

9 
























-26 

88 

76 

64 

52 

40 

29 

17 

5 























-25 

89 

78 

67 

57 

46 

35 

24 

13 























-24 

90 

80 

70 

60 

50 

40 

31 

21 

11 






















-23 

91 

82 

73 

64 

55 

46 

37 

28 

18 

9 





















-22 

92 

83 

75 

67 

58 

50 

42 

34 

25 

17 

9 




















-21 

92 

85 

77 

69 

62 

54 

47 

39 

31 

24 

16 

9 



















-20 

93 

86 

79 

72 

65 

58 

51 

44 

37 

30 

23 

16 

9 


















-19 

94 

87 

81 

74 

68 

61 

55 

48 

42 

35 

29 

23 

16 

10 

















-18 

94 

88 

82 

76 

70 

64 

58 

52 

46 

40 

34 

29 

23 

17 

11 

5 















-17 

94 

89 

83 

78 

72 

67 

61 

56 

50 

45 

40 

34 

29 

23 

18 

12 

7 














-16 

95 

90 

85 

80 

75 

69 

64 

,59 

54 

49 

44 

39 

34 

29 

24 

19 

14 

9 













-15 

95 

91 

86 

81 

76 

72 

67 

62 

58 

53 

48 

44 

39 

34 

30 

25 

21 

16 

11 

7 











-14 

96 

91 

87 

82 

78 

74 

69 

65 

61 

56 

.52 

48 

43 

39 

35 

30 

26 

22 

18 

13 

9 

5 









-13 

96 

92 

88 

84 

80 

76 

72 

67 

63 

59 

55 

51 

47 

43 

39 

35 

31 

27 

23 

20 

16 

12 

8 








-12 

96 

92 

89 

85 

81 

77 

73 

70 

66 

62 

58 

55 

51 

47 

44 

40 

36 

32 

29 

25 

21 

18 

14 

11 

7 






-11 

96 

93 

89 

86 

82 

79 

75 

72 

68 

65 

61 

58 

54 

51 

47 

44 

40 

37 

34 

30 

27 

23 

20 

17 

13 

10 

6 




-10 

97 

93 

90 

87 

84 

80 

77 

74 

70 

67 

04 

61 

57 

54 

51 

48 

44 

41 

38 

35 

32 

28 

25 

22 

19 

10 

13 

9 

0 


-9 

97 

94 

91 

88 

84 

81 

78 

75 

72 

69 

66 

63 

60 

57 

54 

51 

48 

45 

42 

39 

36 

33 

30 

27 

24 

21 

IS 

15 

12 

9 

-8 

97 

94 

91 

88 

85 

83 

80 

77 

74 

71 

68 

65 

02 

00 

57 

54 

51 

48 

45 

43 

40 

37 

34 

32 

29 

26 

23 

20 

IS 

15 

-7 

97 

95 

92 

89 

86 

84 

81 

78 

75 

73 

70 

07 

65 

62 

59 

57 

54 

52 

49 

46 

44 

41 

38 

36 

33 

31 

28 

25 

22 

20 

-6 

97 

95 

92 

90 

87 

85 

82 

79 

77 

74 

72 

69 

67 

64 

62 

59 

.57 

54 

52 

49 

47 

45 

42 

40 

37 

35 

32 

30 

27 

25 

-5 

98 

95 

93 

90 

88 

86 

83 

81 

78 

76 

74 

71 

69 

00 

64 

62 

59 

,57 

55 

52 

50 

48 

45 

43 

41 

39 

36 

34 

32 

29 

-4 

98 

95 

93 

91 

89 

86 

84 

82 

79 

77 

75 

73 

71 

68 

66 

64 

62 

59 

57 

55 

53 

51 

49 

46 

44 

42 

40 

38 

36 

33 

—3 

98 

96 

93 

91 

89 

87 

85 

82 

80 

78 

76 

74 

72 

70 

68 

66 

64 

62 

59 

57 

55 

58 

51 

49 

47 

45 

43 

41 

39 

37 

-2 

98 

96 

94 

92 

90 

88 

86 

84 

81 

79 

77 

75 

73 

71 

70 

68 

66 

64 

62 

60 

58 

56 

54 

52 

50 

48 

46 

44 

42 

40 

-1 

98 

96 

94 

92 

90 

88 

86 

84 

83 

81 

79 

77 

75 

73 

71 

69 

68 

66 

6t 

62 

60 

58 

56 

54 

53 

51 

19 

•17 

45 

43 

0 

98 

90 

94 

93 

91 

89 

87 

85 

83 

81 

80 

78 

76 

74 

73 

71 

09 

67 

06 

64 

62 

60 

59 

57 

55 

1 

52 

50 

48 

46 


Dopression of wet-bulb tlioniiomctcr ((— f'). 


3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.0 

4. 1 

4.2 

4.3 

4.4 

4.5 

4.0 

4.7 

4.8 

4.9 

5.0 

5.1 

,5.2 

.5.3 

5. -1 

5. 5 





6 

12 

10 

7 



























18 

15 

13 

10 

8 

5 
























23 

20 

18 

15 

13 

11 

8 

6 






















27 

25 

23 

20 

18 

16 

14 

11 

9 

7 

5 



















31 

29 

27 

25 

23 

21 

19 

17 

14 

12 

10 

8 

0 

















35 

33 

31 

29 

27 

25 

23 

21 

19 

17 

15 

13 

n 

10 

8 

6 














39 

37 

35 

33 

31 

29 

27 

25 

23 

22 

20 

18 

16 

M 

12 

11 

9 

7 

5 











42 

40 

38 

30 

34 

33 

31 

29 

27 

26 

24 

22 

20 

19 

17 

15 

14 

12 

10 

8 

7 

5 








45 

43 

41 

40 

38 

36 

34 

33 

31 

29 

28 

26 

24 

23 

21 

20 

18 

16 

15 

13 

11 

10 

8 

7 

5 






Air terapera- 
titre(0. 


PART II. THE USE OF PILOT BALLOONS. 


1. SELECTION OF STATIONS AND OBSERVATION POINTS. 

Observations with pilot balloons are made for the 
purpose of determining wind direction and velocity at 
various altitudes; also the height, direction, and velocity 
of clouds whenever the balloons enter their bases. The 
apparatus and methods used are described in detail in 
the following sections. Briefly, the observations are 
made by following with a theodolite the flight of small 
rubber balloons filled with hydrogen. The angles of 
azimuth and elevation are observed and recorded, and 
these data, together with the balloon’s altitude at suc- 
cessive intervals of time, make possible the construction 
of a horizontal projection of the path followed and the 
determination from this projection of wind direction and 
velocity at various levels. 

Generally speaking, the selection of a suitable site for 
this work is simpler than is that for observations by 
means of kites, and it is therefore practicable to make 
pilot-balloon observations at all kite stations, a descrip- 
tion of the principal requisites of which has already been 
given. In addition, they can be and are made at many 
other places not suitable for kite work, even in populous 
cities, provided these arc comparatively free from factory 
smoke, etc. 

Pilot-balloon stations are of two kinds, viz, “single- 
theodolite” and “double-theodolite” stations. Simi- 
larly, methods of observation are known as “single- 
theodolite” and “double-theodolite” methods. 

By the first method the theodolite is set over a fixed 
point and oriented with zero of the azimuth circle on 
either a north or a south point. The balloon is assumed 
to rise at a constant rate of speed. Computation in- 
volving the ascensional rate, elevation angle, and azi- 
muth angle determines the position of the balloon. By 
the double-theodolite method, two theodolites are ho- 
mologously oriented (that is, with zeros of the azimuth 
circles in the same direction), one at either end of a defi- 
nite base line. Computation involving the length and 
bearing of the base line and the observed azimuth and 
elevation angles determines the horizontal position of 
the balloon and its height above the surface. 

Since the two methods have so much in common, 
and since the majority of the stations now in operation 
are, and probably most of those of the future will be of 
the single-theodolite type, these instructions will treat 
chiefly of the single-theodolite method. However, de- 
partures from this method applicable to the double- 
theodolite method will be fully considered herein. 


The selection of an observation point for single-the- 
odolite work will be determined by the following: 

(a) Geographical location. 

(b) Low horizon. 

(c) Angular altitude of obstructions. 

(d) Convenience to oflice. 

In addition to the above, double-theodolite work will 
also depend upon — 

(e) Base line, length, and bearing. 

(/) Unobstructed view along base line. 

ig) Common level of primary and secondary 
points. 

The shape of the earth’s surface and the obstructions 
on it influence the surface winds and the winds aloft in 
the lower levels. When the surface is abnormal or the 
obstructions are pronounced, the local influences will 
be met with through 1,000 or 1,500 meters in elevation. 
Therefore, if these modifying influences are so marked as 
to cause divergence from the normal wind conditions, 
the data obtained will be abnormal and local rather 
than normal and of the general wind circulation near 
the surface. And, since we are more interested in the 
conditions of the general circulation than of the local 
influences, a choice of station must be made which will 
give as nearly as possible wind data little affected by 
local influences. 

An ideal observation point would be in the open, level 
country or on the crest of a slight rise. The ground 
should be firm and the position well removed from build- 
ings and tall trees that might interfere with the lino of 
sight upon the balloon. The maximum angular altitude 
of obstructions such as buildings and trees should never 
exceed 0 degrees above the sensible horizon. Smoke- 
stacks and chimneys in close proximity to the station give 
much annoyance and should be avoided, if possible, since 
even slight amounts of smoke 1 herefrom are suflicient to 
obscure the balloons. 

The observation point should be as convenient to the 
administration oflice as satisfactory location will permit. 
In single-theodolite work this may well be on the roof of 
the oflice building or on one near by. In double-theodo- 
lite work either primary or secondary point, and some- 
times both, will necessarily be a little distance from the 
administration oflice. 

The, observation point for single-theodolite work may be 
any convenient })oint from which, as far as possible, an 
unobstructed view may be obtained. Since most of the 
administration oflices are located in or near cities or large 


55 


56 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


towns, satisfactory ground conditions with convenient 
location will seldom be found. The next in order will be a 
position on a flat-roofed, well-exposed building. In the 
selection of such a site due consideration must be given 
to superstructures such as towers, penthouses, cupolas, 
etc. Where it becomes impracticable to observe from 
the top of the superstructure itself, a position to one side 
of the structure, and sometimes one also on the opposite 
side, will answer. Many instances will arise in which the 
range of vision is affected only by the central structure. 
When this is not too high, the difficulty may be overcome 
by erecting upon the main roof a platform from which 
to observe, but, in general, two points of observation, one 
on either side, are preferred to one on top, inasmuch as 
by the latter method stability and rigidity are likel}^ to be 
diminished. In selecting the observation points on a 
roof having a central structure it is well to consider the 
prevailing wind direction for the station. The observa- 
tion point should be selected on the leeward side and as 
far removed from the central structure as extent of roof 
will permit. 

The geographical location of a double-theodolite station 
is not materially different from that of a single-theodolite 
station. Low horizon and angular altitude of obstruc- 
tions have a similar application in either case. A double- 
theodolite station is provided with two theodolites, one 
at either end of a suitable base line. The station at 
which the balloons are prepared and released may be 
known as the “primary station,” “home station,” or 
“station A.” The second may be known as the “sec- 
ondary station,” “field station,” or “station B, C, etc.” 
The system of base lines should be carefully laid out and 
should radiate from the primary station. 

The major base line should be about 2,000 meters or 
more in length and nearly at right angles to the direction of 
prevailing wind for the station. Minor base lines should be 
laid out as nearly as possible in a direction that will afford 
the best possible results when the surface wind direction 
is other than the prevailing direction. Two base lines 
are sometimes sufficient, though three or more will afford 
a wider choice in selecting the base line at the time of ob- 
servation to give the best results for the current wind con- 
ditions, for in double- theodolite work a base line as nearly 
as possible at right angles to the wind direction aloft is 
invariably used. Computation is simpler and the re- 
sults more accurate. A base line nearly parallel to the 
movement aloft is to bo avoided. 

The view along the base line from either station must 
be entirely free from obstruction. Each station must be 
in plain sight of the other in order to facilitate signaling 
the release of balloon at the primary station and the dis- 
appearance of the balloon at either station. 

The angular elevation of obstiaictions at the secondary 
station, in the direction of the primary station, along 
either side of the base line must be low enough to pre- 
vent interference of line of sight u})on the balloon as it 
moves away from the primary station in strong winds. 


Under ordinary conditions there will be little difficulty, 
but when strong surface winds prevail, especially if 
blowdng across the base line, the change in azimuth 
angle will greatly exceed the change of elevation angle 
at the secondar}^ station. Therefore the elevation 
angle at the secondary station for the first few minutes 
will be low. 

Both stations should have about the same elevation; 
otherwise, computations from the two stations wall show 
a difference in elevation of balloon equal to the differ- 
ence in elevation of the two stations. Therefore, an 
altitude correction equivalent to the difference in level 
of the two stations must be applied to the elevation of 
the balloon as computed from the data at the secondary 
station. Tliis correction will be added when the second- 
ary station is higher than the primary station and de- 
ducted when it is lower. 

The observation points, whether for single- or double- 
theodolite work, must be marked permanently. If the 
point selected is on the bare earth, an iron pipe about 
3 feet long may be driven into the ground until quite 
rigid. A wooden peg is then set in the upper end of 
tins pipe and a small nail or tack in the end of the peg 
marks the exact point of observation. If the position is 
on a graveled roof, the point may be marked by setting 
a small bolt or screw in cement over the point desired. 
Whenever it becomes necessary to use a platform for 
observation, a nail may be driven into the planking. 
Any method whereby the point is permanently marked 
is acceptable. 

Whenever it is necessary to do observational work 
from a platform, the latter will be so constructed that 
no vibration will be transmitted from it to the theodo- 
lite. This is accomplished by building a second plat- 
form or support for the theodolite, in such a way that 
there is a space and no immediate connection between 
the two. Figure 34 shows a section of such a platform 
and theodolite stand. Three posts in the form of an 
e(juilateral triangle, about 36 inches from center to 
center, arc substantially arranged and rigidly braced. 
When secured about the observation point, caps for the 
theodolite foot blocks are placed over the posts in a 
common horizontal })lanc. The observation platform 
is then constructed with tlie u})j)er stirfacc of llooring 
Hush with the toj) of the theodolite foot block but not 
in any way connected with the theodolite stand. A 
space of at least half an inch should be left between the 
two. The observation point will be the common center 
of this e(iuilateral triangular inclosure. As a common 
center, and along the major axis of the theodolite foot 
blocks, lay off ecjual distances from the observation 
point, and start holes with brace and bit half an inch in 
diameter to receive the tips of the theodolite legs. Let 
the holes on each foot block be about 1 inch apart. The 
size and shape of the platform may be arranged to suit 
the needs of the station force, but the general scheme 
above outlined should be followed and the construction 


57 


INSTRUCTIONS FOR AFJIOIXKHCLVL OBSP^RVERS. 


imvdp »u? rigid ns possiiile. Any plan whoroin tlie obser- 
vation platform is well insulated from the theodolite 
stand and rigidly eonstructed will answer. Note that 
in figure 38 observation platform (o) and theodolite 
stand (t) are entirely separated. The only vibration 


far superior for balloon work. A small telescope is 
mounted over a hoi-i/.ontal circle in such manner that it 
tnrns on a horizontal axis through the center of the 
horizontal circle and revolves about the vertical axis 
passing through the horizontal axis. 



CvJ 

cr> 

oi 

D_ 

LU 

C/) 


transmitted to the theodolite is the vibration of the 
roof of the building. 

2. THEODOLITE. 

The theodolite, figure 35, is a specially designed and 
constructed instrument similar in many respects to the 
transit yet possessing distinctive features which make it 


The telescope is bent through an angle of 00 degrees, 
'^riie eyepiece is produced through the angle of the bend 
to act as the horizontal axis of the telesco|) 0 , while the 
object end turns freely in the vertical plane about this 
axis. In a cubical chamber about the right-angle 
bend of the telescoj^e a 45-degree triangular jirism, 
acting as a mirror, is rigidly fixed in such a jjosition that 


58 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


the shorter sides of the prism are perpendicular to the 
central line along the two tubes. The function of this 
prism is to turn the line of sight with the bend of the 
telescope and give a clear, well-defined image. The 
eyepiece is further provided with cross hairs stretched 
over a reticle for centering the objective and a rack and 
pinion for focusing the telescope. The objective end 
termmates in a cylindrical sleeve, which acts as a sun- 
shade to protect the object lens. The mass of both eye- 
piece and object end of telescope are compensated by 
counterweights, thus providing a free, even movement of 
little resistance. 

The telescope is supported over the center of the hori- 
zontal plate by a yoke standai’d. A vertical circle for 
elevation and a horizontal circle for direction are pro- 
vided for determining the I’elative movement of the 
telescope. Both vertical and horizontal circles are 
graduated in whole degrees. More accurate readings 
may be made by using verniers. Essentially, the vernier. 




Fig. 36.— Theodolite vernier. 


figure 3G, liv, consists of a small graduated scale the unit 
divisions of which are just a certain amount smaller than 
the divisions of the scale upon which it is applied. This 
is accomplished on the circles of the theodolite by taking 
a space equal to 9 degrees, laying it off on the vernier, and 
dividing it into 10 equal parts. In ligure 36, drawing 
A, let lie ha the horizontal circle divided into degrees, 
and liv the horizontal vernier. Note that while the zero 
of both lie and liv are coincident, the tenth division of 
liv is coincident witli only the ninth division on Tie. 
Thus, each division of hv is one-tenth degree less than 
each division on lie. When two such scales are placed 
together, some particular line of the one will always be 
coincident or nearly coincident, with one of the divi- 
sions on the other. The position of the coinciding divi- 
sions, or the nearly coinciding divisions, determines the 
vernier reading. For example, when the third, fourth, 
or sixth division of liv is coincident with some division 
on Ue, the fractional parts of degree will bo 0.3, 0.4, 


or 0.6, respective!}^. On drawing B of figure 36, the ver- 
nier reading is 0.6 of a degree, and on drawing 0, it will 
be noticed that no one division of Itv is coincident with 
any other of the scale lie but that the seventh and 
eighth of liv are both between two of the divisions of He, 
which shows that the vernier reading is more than 0.7 
and less than 0.8 of a degree. The second place of the 
vernier reading must be gained by estimating the frac- 
tional part of one of the vernier divisions, which is rep- 
resented by the space between 6 on He, and 7 on hv. 
In drawing (7 of figure 36, this space is about half of 
one-tenth, or 0.05 of 1 degree. Thus we see the vernier 
reading in this particular case is 0.75 of a degree, which, 
added to the index reading of the scale, determines the 
degrees and liundrodths. The practical application of 
these verniers is shown by the sectional wew of the 
theodolite in figure 37. The accompanying table gives 
the reading of each vernier in figures 36 and 37. 



VI' 

HV 

hv 

Fipire 36 A 



0.00 

Figure 36 B 



.60 

Fi^re 36 C 



359. 75 

Fi^ire 37 

85.71 

00.00 

315.00 



The levels are arranged on the horizontal plate, one 
parallel to the horizontal axis called the plate level, PL, 
figure 35, while the other, perpendicular to the first,, is 
known as the standard level, SL, figure 35. 

The instrument thus far assembled revolves about a 
vertical axis, whose bearing is a sleeve and spindle, at 
the center of a graduated horizontal circle known as the 
base plate. An extension of the vertical axis, or the 
sleeve and spindle, passes through the shifting center 
and terminates in a spring and knurled nut to form the 
shifting center tension. The base plate is capable of 
revolution about this center but is ordinarily held in a 
rigid position by plate clamp screw, P, figure 35. The 
shifting center, S, assembled with and encircled by a heavy 
ring or handle, 77, is supported above the tripod head, 
T, by means of three leveling screws, Li^. Each leveling 
screw is provided with a tcjision or clamp screw, L. 
Pendent from the vertical axis and center of instrument 
VA is a small chain and hook, p, for the attachment of 
the plumb bob and line. 

Af^Hemhling the theodolite. —Assuming that the crates 
have been removed and that no damage has been done 
either in shipping or unj)acking, the tripod will be opened 
up and planted firmly upon the lloor with legs well spread 
aTid securely set to prevent slipping. Loosen the milled 
tension nut of the shifting center, figure 35, and run 
well down to the knurled head of s|)in(lle. Then remove 
the round wooden cap. Loosen the shifting-center nut 
or clamp ring, ('R, figure 35, and adjust the shifting center 
S, so that tlie seats of the levcliug screws, LS, are sym- 
jiietrically arranged over their respective plates of the 
tripod head T. After tightening the clamj) ring to 
retain the shifting c.entcr in that |)osition, the triiKxl is in 
readiness for the instrument itself. 



'A'l . — I'lieoilolilc used in kiln nml l)nllooii work (Ji , liuck of iiislniriictil. ; H .\ , l)ul)lilo adjiisl mcid scn'W ; 
II1‘, l)as('. phUo; (', cap or cover hlock; f'A', claiii|) riii);: ('U\ liack coiiiiicrwcit'ld ; cir, from (•(Miidcr- 
wciKld ; A, I'ycpiccc: /, fociisiiit; screw; />', front (d inslrnincnt ; //, Iniinilc or riiif!: //.I, liorizonlai 
axis; //C, tiori/.onlal circle; /(C, iiori/.onial linib and l.'i'’ vernier; // 1, liorizonlai limb and riKld vernier; 
//'/', liorizonlai lanp'eiil screw; A, levelint; clani)i screw; A.S, leveliii)' screws; p, pliinili bob hook; 
/’, plale clamp screw; /’A, jilale levid or bubble; /’//, prism boiisiiiK; A'.S', reliele screws; .S', sbitling 
center; .S'A,, slandard level or bubble; .S'.S', sun shade; .S’7', shift iiit; eeiiler tension; 'A, Iripod head; 
'/'.S’, teleseo]ie stoji; I'.-l , verlieal axis; vertical circle; I'l', verlieal limb and vernier; 1'/', verlieal 
tangent screw; 1", yoke standard). 



Fi(}. 'M . — Soclion of t lu'odolif c showing' arran"(*m(Mil of \ oniic'rs \s iUj horizontal 
and veil ical circles (// r, horizonl.nl lini b and rijilil. vernier; hi , liuri/.onlal iinil) 
and l.‘>® vernier: IT, vertical circle; 11 , vertical limb and \ernier). 




INSTRUCTIONS FOR AKROLOOTCAL OBSERVFRS. 


59 


In most cases it will he found that the telescope has 
been removed from its hearings and packed in a se])arato 
rack in (he case above the carriage. When so packed, 
the procedure will he as follows: The door of the theodo- 
lite case must he wide open to allow the removal of the 
lower shelf supporting the assembled yoke standard, base 
plate, and shifting center. These parts, so assembled, wdien 
removed from the case arc placed upon a table or heneh. 
With a (inn grip on one edge of the shelf or rack tilt the 
whole upon one edge to allow access to the underside 
where a brass thumb nut retains the assembly to the rack. 
Unscrew this thumb nut but do not remove instrument 
from rack. When returned to the initial position as it 
was placed on the table or bench, remove the string tied 
about the horizontal tangent screw and right telescope 
stop, HT and TS, figure 35, and disengage tangent screw 
from horizontal circle, IJC, by pulling the head of the 
screw away from tlie circle. Turn the yoke standard 
and base plate upon its axis, VA, until both elevation 
and azimuth tangent screws, FT and HT, are on the 
extreme right; then throw in the azimuth tangent screw, 
HT, to retain the base plate in that position. The two 
telescope bearings of the yoke standard will now be equi- 
distant from the observer as he stands before the 
instrument. 

With a small thin-bladed screw driver, remove the 
screws in each end of the cap or cover block, C, over the 
telescope bearing of each yoke standard, Y. Remove 
each cover block carefully, with both screws in their rela- 
tive positions in the block, and lay to one side in .such a 
manner that there will be no confusion as to the exact 
position from wdhch it was removed; that is, observe that 
the screws are not clianged about in the immediate cover 
block and that the cover blocks do not become exchanged 
for one another, or reversed end for end. In short, when 
they are replaced see that they are in no other position 
than that from which they were removed. The carriage 
is now ready for the telescope. 

The telescope is removed from the shipping case in the 
same manner as is (he carriage itself. It is placed upon 
the table by the side of the carriage and with the object 
end of the tc'lescope toward the observer. To set upon 
tlie standard, grasj) the telescope at both ends of the 
main tube and, holding in this position, move to the 
carriage and carefull}^ set in its bearings, which, if the 
j)reccding instructions have been carried out, will be 
properly set to receive, (hiution: Do not let moisture 
or oil from the hands come in conta<’t with the brass 
bearitigs of either telescof)e or yoke standard; likewise 
the silvered vertical circle and verni(>r. Note that the 
graduations on the vertical circle are coincident with the 
vernier on tin; right standard. Making sure that the 
tclesco])e is lirmly set in its bearings, replace the caps or 
cover j)latcs in tliesanu' position as that from which tlnty 
were removed, d'urn in the screws firmly but do not 
force them. Unde.r no consideration should the leather- 
ized bushing screw at the middle of the cover plates or 


the Y-block screw on the underside of the left bearing be 
touched at this time. These materially aflect the ad- 
justment of the instrument and should not be disturbed. 

Replace the brass cap on the object end of the tele- 
scope with the aluminum cylinder, or sun shade, found 
in the back right-hand corner of the shipping case. The 
function of this shade is to protect the object lens, and 
the instrument should never be used without it. Direct 
rays of the sun or strong light will cause the cement 
between the sections of the object lens to run to one 
side, causing a "fern leaf” which interferes with the 
visibility tlmough the lens. The cap on the axis of the 
telescope, just above the right horizontal tangent screw, 
is now removed. The eyepiece is taken from its rack in 
the back left-hand corner of the shipping case, freed from 
its protecting cap on the lower end, where it is screwed to the 
axis of the telescope in place of the cap which was just re- 
moved therefrom. This eyepiece is provided with a spe- 
cial pivoted attachment containing a disc of colored glass 
(dark green) for use when the the balloon is near the sun. 

The assembled instrument is now lifted from the sup- 
porting rack by the ring or handle and carefully placed 
upon the tripod, making sure that the chain and hook, 
p, figure 35, drop straight through the hollow spindle of 
shifting center ST, and that the three leveling screws, 
LS, are properly seated in the grooves in the respective 
arms of the shifting center plate. Insuring that the ten- 
sion nut is run down well to the knurled end of the 
spindle, the shifting center tension, -S' T, is now raised 
until the threaded socket engages the tlu’eaded end of 
the vertical axis, VA, and turned on securely. The ten- 
sion nut is then run up on the spindle to compress the 
spring and hold the instrument firmly on the tripod. 
However, the mit must not be run up too far, so that 
there is no room left between the turns of the spring for 
ecpializing the adjustment of the leveling screws. The 
theodolite is now completely assembled, and after adjust- 
ment and checking will be ready for observation work. 

Care of the theodolite . — The theodolite, being a delicate 
and costly instrument, should be given particular care 
and attention. It should never be left standing without 
the assurance (1) that the instrument is securely fastened 
upon the tripod, accomplished by the complete union of 
the vertical axis of instrument with the spindle of the shift- 
ing center tension; (2) that the tripod is well opened— that 
is, the fre(^ ends of the legs not too close together; and 
(3) that the h'gs are firmly planted to prevent slipping — 
a slight pre.ssure of the foot upon the projecting plate of 
the tip of the trifxxl leg will accomplish the last. 

When left standing, the instrument should be pro- 
tected fiom all dust ami foreign matter by covering with 
a light cloth and fretpiently wiping otf the exposed parts. 
Should it becoim* necessary to remove dust or moisture 
from the object lens, only a clean, dry chamois should 
be used cm the exterior side of the lens. The lens is not to 
be removed from the tube for this purpose. The joints 
and seams of the telescope are so closely fitted that it is 


60 


INSTEUCTIONS FOE AEEOLOGICAL OBSEEVEES. 


practically impossible for dust to get on the inside of the 
tube. Therefore, there will be no reason for taking the 
instrument apart for cleaning purposes. The lens at the 
eyepiece will rarely need this attention, and in such event 
is easily accessible by removing the aperture disk only 
on the extreme end of the eyepiece or front of the tele- 
scope. Attempts at further removal and cleaning of this 
lens are most certain to result in the destruction or dis- 
arrangement of the cross hairs on the reticle. 

Special attention should be given to the tangent screws 
of both vertical and horizontal circles. A little light clock 
oil in limited amounts and applied properly will eliminate 
much friction and reduce the wear on the base plate. 
Close examination of the instrument from time to time 
will reveal small parts and screws which have become 
loosened. These should be attended to immediately, so 
far as possible without the interference of proper adjust- 
ment; that is, if the parts which have become loosened 
materially affect the adjustment of the instrument it will 
be necessary to readjust and check the instrument after 
such parts have been tightened. 

The instrument is not to be taken apart more than is 
necessary for packing and shipment. Further taking 
apart for the purpose of cleaning or repairs should be 
done only by one experienced with the construction of 
the instrument, or by a competent person, and upon the 
receipt of authoritative instructions from the Central Office. 

Care should be taken that the hands do not come in 
contact with silvered surfaces of the circles or the verniers, 
for the moisture and oil thereby deposited tend to oxidize 
the surfaces, making the graduations indistinct and diffi- 
cult to read. If these parts do become tarnished they 
may be brightened to some extent with a soft rubber 
pencil eraser. 

Pacldny the theodolite— 'Whenever it becomes necessary 
to ship the theodolite, a great deal of care must be given 
to the packing and prcjiaration for shipment. The pack- 
ing case in which the instrument is received should be 
preserved for this purpose. The style of case ordinarily 
used necessitates the separation of telescope from the 
assembled standard and base plate. This is accomplished 
by reversing the instructions given in section 2, under 
'' A.ssembling the theodolite.” In addition, the hori- 
zontal tangent screw 11 T, figure 35, is to bo thrown in 
mesh with the base jilate BP and secured there by wrap- 
ping and tying a short length of string about the hori- 
zontal tangent screw UT and telescope stop TS. See 
that the vertical tangent screw FT is disengaged and 
that the base-plate clamp screw P is loosened. Place 
the assembled standard and base plate, which has been 
secured to auxiliary shelf for that purpose, in the bottom 
part of the case so that the right horizontal vernier 7/F 
is about midway and toward the front of the case. Now 
prepare 4 rolls of excelsior about 6 inches long and 2 
inches in diameter for packing the assembled standard. 
These rolls are to be placed one on either side of each 
telescope standard, in such a way that the ends of each 


roll will be against the side wall of the shipping case and 
the right or left edge of the telescope standard. When 
the last of these excelsior rolls is in position the telescope 
standard will be held rigidly from moving about on the rack. 
In placing the excelsior roll against the left hand edge 
of the forward yoke standard be sure that it does not press 
too hard against the vertical tangent screw VT, figure 
35. The telescope, with sunshade and eyepiece tube 
removed, is then laid in its supporting rack and placed 
in the upper part of the shipping case, with a piece of 
folded paper inserted between the telescope tube and 
the stay-blocks on underside of top of packing case. 
After closing and securely locking the door, fasten the 
key to case by means of a screw through the head. 
Each theodolite should be packed in its own case — that is 
the case bearing the same serial number. For shipment 
from station to station the shipping case containing the 
theodolite must be substantially crated. 

Carrying the theodolite. — The best method for carrying 
the theodolite is shown in figure 38. This position is 
obtained from the standing theodolite as follows: The 
observer, with the instrument close to his left, grasps it 
firmly on opposite sides of the ring or l\jxndle, then, placing 
his right foot in front of the nearest leg of tripod to prevent 
slipping, pushes the instrument forward to rest entirely 
upon that one leg and closes the others in by its side. 
Eesuming the handhold upon the ring and turning a little 
to the right, followed by a step forward, will allow the 
observer to place the left hip in front of the closed tripod, 
and a second step forward with the lowering of the instru- 
ment head turning over the hip as a pivot will obtain the 
illustrated position. The advantage of carrying the 
instrument in this manner, rather than over the shoulder, 
is that the particular part of the instrument needing the 
most attention is right before the observer where he can 
watch it while passing through doorways, up and down 
stairs, or close to walls and buildings. When the theo- 
dolite is carried over the shoulder, the mass of the instru- 
ment itself exerts a strain upon the vertical axis, FA, 
figure 35, but when carried in the above-described position 
the strain is overcome, since the mass of the instrument is 
supported by the ring or handle designed for that purpose. 
It also affords more ease and comfort to the observer if 
the instrument is to be carried any distance. 

Adjustments of the theodolite.-- Before the new theodolite 
is used it must be thoroughly adjusted and checked. 
This will bo done at the Central Oflice before the instru- 
ment is assigned to a.ny station. However, due to rough 
handling in shipment, it Ixecomes necessary to recheck 
and sometimes to readjust the theodolite at the lield 
station. An instrument in daily use should be checked 
occasionally- at least once every four months. If the 
initial adjustment is carried out carefully and accurately, 
these periodic corrections will be slight if at all noticeable, 
yet they should not be neglected. 

When the theodolite adjustment has been completed, 
the entire series of tests should be gone over as a means 



Klii. 38.— I’ropcr incthoil of carrying Iticodolile, and insulation of tlicodolilo sland ( jf'jfrom observa- 
tion platforin (O). 


r 


ii 


\ 




INSTRUCTIONS FOR AP:R0L0(JICAL OBSERVERS. 


61 


of checking. It will often be fonml necessary to make 
slight corrections which oxeinplil'y the need of much 
attention during the initial adjustment. Before making 
any one of the adjustments, note that the instrument is 
properly seated at leveling screws and that the horizontal 
base plate is level. Check for levels before each of 
adjustments 2, 3, and 4 is attempted. 

The instructions for the adjustment and checking of 
instruments follow and are to be closely adhered to. 
They were prepared by Mr. William C. Haines, Observer, 



as the result of extended experience with these instru- 
ments. 

The adjustments of the theodolite are such as to cause 
(1) the instrument to revolve in a horizontal plane about 
a vertical axis, (2) the line of collimation to generate a 
vertical plane through the instrument axis when the 
telescope is revolved on its horizontal axis, and (3) the 
vernier on the vertical circle to give true readings of the 
angle of elevation of the line of collimation. These results 
may be brought about by the following adjustments: 

1. The plate-level adjustment: To make the axis of 
each plate level lie in a plane perpendicular to the vertical 
axis, bring one of the level tubes in line with two of the 
levelmg screws. Level with 

leveling screws, revolve the 
instrument 180° in azimuth, 
correct one-half the move- 
ment of the bubble on the 
leveling screws and the other 
half by raising or lowering 
the adjustable end of the level 
tube. Now level up again and 
revolve 180°, and the bubbles 
should remain in the center. 

If not, adjust for one-half the 
amount as before, and so con- 
tinue until the bubbles re- 
main in the center for all posi- 
tions. 

2. The collimation adjustment: To make the line of 
sight perpendicular to the horizontal axis of the telescope. 
When this is done the line of sight will generate a plane 
when the telescope is revolved on its horizontal axis. 
Set up the theodolite on level ground whore a view can 
be had in opposite directions. (If the ground is not level 
a small error may be introduced into this tost due to the 
horizontal axis.) With the telescoj)e pointing to the 
left, set the line of sight on a definite point A, figure 39, 
a few hundred feet away. Revolve the telescope about 


its horizontal axis and set another point /i in the opposite 
direction. Now rotate the instrument in azimuth until 
the line of sight comes upon the first point A. Revolve 
the telescope about its horizontal axis again and fix a 
third point C on the line of sight beside the second point 
B. From the last point set, measure off one-fourth the 
distance between these two points to a point D and 
bring the line of sight to this position by moving the 
reticle laterally. This movement is reversed in the 
theodolite, as it is an inverted instrument. This adjust- 
ment should be repeated as a check. 

It is often found that the line of sight can not be 
brought to position without moving the reticle too far 
from the center of the tube. In this case adjustment 
must be made on the 45° glass prism which is placed 
in the cube at the axis of the telescope for the purpose 
of deflecting the line of sight at right angles. Unless the 
reflecting surface of the prism makes an angle of 45° with 
the incident beam of light, the deflection is no longer at 
right angles, but may be either greater or less than 90°, 
depending upon the relative position of the prism. 

Before attempting to adjust the prism, first determine 
whether the angle of deflection is greater or less than 
90°. This may readily be done from the above test. 
If point C, the last point set, falls to the left of point B 
(the observer facing the points), the angle of deflection 
is apparently less than 90°. If it falls to the right of 
point B, the angle of deflection is apparently greater than 
90°. The reverse of the above is actually true, however, 
because of the fact that the theodolite inverts the objects. 
In the first case the angle of deflection is in reality greater 

fi' 


1 yic i^Ce « i ^ b<a.>y t 
/A 



r^ 

V 

Pv 

1 

? / X 

(bl 

R 




>’ O'L 

c5> q. / 

o. 

/ 


0 

L 



N - M' 

Fig. 40. — F:ilcct of prism on line of sight. 

than 90°, and the prism must be moved so as to increase 
the angle made by its reflecting surface to that of the 
incident beam of light. In the second case the angle of 
deflection is in reality less than 90°, and the reflecting 
surface must be moved so that it will make a smaller 
angle with the incident beam. In figure 40 (neglecting 
the effects of refraction of light in the glass) (a) shows 
position of prism with reference to incident beam of 
light to cause deflection greater than 90° and (d) posi- 
tion to cause deflection less than 90°. 


62 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


To make this adjustment, the prism must l)e removed 
from the telescope. This is accomplished by removing 
the small brass screws from the plate covering the cube 
at the axis of the telescope. The prism is attached to 
this plate and is removed with it. Two set screws hold 
the prism in position on the plate. Its reflecting surface 
may be moved with reference to the line of sight by 
loosening one set screw and tightening the other. Care 
should be taken not to overadjust the prism, for a glance 
at figure 40 will show that any movement in the reflecting 
surface to the incident beam of light will be doubled in 
the reflected rays. In this instance, the assumed move- 
ment of 5 degrees in the reflecting surface produces 10 
degrees difference in the angle of deflection. In so far 
as the deflection of the line of sight is concerned, the 
45-degree prism produces the same effect as a plane 
mirror placed in the position of the reflectmg surface of 
the prism. Any refraction that is produced at the en- 
trant face of the prism is nullified by corresponding re- 
fraction on emergence of the ray of light. 



3. The standard adjustment: To make the horizontal 
axis of the telescope perpendicular to the vertical axis 
of the instrument, carefully level the theodolite and sight 
on some high point, as a steeple S, figure 41, lower the 
telescope and set a point R below S on about the same 
level as the instrument. Revolve the telescope about 
its horizontal axis and turn the instrument upon its 
vertical axis and again sight at S. Lower the telescope 
as before and set a point L opposite R. A point S' mid- 
way between R and L must be in the same vertical plane 
with S. Now raise or lower the adjustable end of the 
horizontal axis by means of the capstan-headed screws 
at the one end of the axis. The high end of the axis is 
always on the same side as the last point set. If this 
end of the axis is not adjustable, the other end can be 
raised instead. The test should be repeated until the 
line of sight coincides with S S'. Care should be taken 
to leave the cap screws tight enough to insure that tlie 
axis rests on its bearing but not tight enough to cause 
friction in turning the axis. 


4. The vernier adjustment: To make the vernier read 
zero when the line of sight is horizontal. This adjust- 
ment is usually made by one of the peg methods. The 
following is perhaps the simplest: 

The instrument is set up midway between two pegs 
N and S, figure 42. With the vernier set on zero the rod 
is held and read on these two points. Care should be 
taken that the vernier setting is not disturbed while 
making this test. Even if out of adjustment the dif- 
ference between the rod readings gives the true difference 
in level between N and S. The instrument is next set 
up near the higher peg so that looking through the tele- 
scope with the eye at the object end a point can be set 
in the exact center of the small field of view and the 
reading taken. The rod is next held on the distant peg 
and read in the usual way. If the true difference in 
level between the pegs be added to the near peg reading 
it will give what the distant rod reading should be if the 
instrument is in adjustment. The difference between 
this amount and the actual distant rod reading represents 
the error in adjustment. To correct the error, set line 
of sight on correct reading on distant rod, then shift the 



Fig. 42.— Peg adjustment. 


vernier and carefully adjust it to read zero in this new 
position. 

Setting up theodolite for observation . — Place the theo- 
dolite over the observation ])oint so that the base plate 
of the instrument is nearly level and centered over the 
exact point selected. To do this, see that the tripod is 
well opened, with legs firmly and symmetrically im- 
planted about, and equidistant from, the exact point. It 
is well to arrange the theodolite, when setting up for 
observation, with plate clamp screw, P, ligure 35, on the 
opposite side of vertical axis, FA, from the orientation 
point which is being sighted upon. The signilicance of 
this will be understood later. 

To level the theodolite, turn the telescope upon the 
horizontal axis II A, ligure 35, until it is about perpen- 
dicular to the base plate (the verlical circle set at or 
near 90 degrees, see reading of 11’, ligure 37). Disen- 
gage the horizontal tangent screw IIT, ligure 35, and 
turn the instrument about its vertical axis until one of 
the levels, preferably the standard level SL, is parallel 
with the line joining any two of the leveling screws, 
LS. As a guide for this setting bi-ing the right luu'izontal 
vernier, II V, over one of the three spokes of the ring or 
handle, and use the leveling screws oJi each side. See 


INSTUUCTTONS FOR AEROLOGICAr. OBSERVERS. 


63 


that tho sliiftin" center tension spring is suflTieiently 
loosened to allow ample adjustment of leveling screws, 
then bring the bubble between the marks of the standard 
level by turning the two leveling scitws in oj)posite 
directions; that is, both in or both out as the oc<^asiou 
demands. While in this position, adjust plate level, 
PL, by raising or lowering with third leveling screw. 
Attach plumb bob to hook and chain, j), pendent from 
the vertical axis, and adjust until the bob just swings 
freely over the point. When the bob comes to rest, if 
not centered over the point of observation, loosen the 
thumb plate, CR, clamping the triangular shifting center, 
S, and shift theodolite head to the position in which the 
point of the plumb bob, when at rest, is pendent directly 
over the observation point, then lock by means of the 
thumb plate. If necessary, relevel the instrument by 
the above method, noting that each bubble is equally 
spaced between the marks on the appropriate tube. 
Now turn the instrument about its vertical axis 
successively through 90, 180, and 270 degrees, and 
observe that the bubbles are still in the central positions. 
If they are not, then return the telescope to the initial 
position and readjust until this is accomplished. 

The theodolite now being leveled, turn the instrument 
about its vertical axis until either the right horizontal 
vernier, HV, figure 35, or the 45-degree horizontal 
vernier, hv, figure 35, is set on the azimuth bearing of 
the reference point, then lock by throwing in the hori- 
zontal tangent screw, HT. Set the vertical circle of the 
telescope at or near zero, loosen plate clamp screw and 
turn the locked telescope and base plate about the 
vertical axis until the telescope is sighted upon reference 
point of orientation, accomplished by means of the ball 
and V sights along the main tube of the telescope. Be 
sure that the azimuth setting on base plate for the par- 
ticular reference point has not been disturbed, then lock 
base plate to the horizontal axis by tightening the plate 
clamp screw P. 

Upon sighting through telescope, if it is found that 
intersection of cross hairs is not coincident with roh'rence 
point, raise or lower by means of the vertical tangent 
screw, VT, and shift horizontally by means of the slow- 
motion or base-j)late adjustment screw. This (hial hori- 
zontal adjustment must not be made willi the hoilzontal 
tangent screw, since this would disturb the orientation 
setting of the particular reference point. 

Adjustment of the eye[)iece, by turning the aperture 
disk either in or out, to obtain the maximum shai])ne.ss 
of cross hairs, and focusing tho telescope by use of the 
rack and pinion, will complete the orientation and setting 
of the theodolite for observation work. 

Orientation of the theodolite is the process of placing 
the telescope in the vertical plane of a particulai- meridian 
and is accomplished by the method which immediately 
preccfles. However, before orientation can Ixi accom- 
plished, the exact position of a north-south line must be 
determined, and this line must also he determined for 


each point of observation, with the exception of second- 
ary stations at the far end of a base line, 'khe line for 
this observation point may be derived from the azimuth 
bearing of base line from the prifnary station. Three 
distinct methods arc here given for the determination of 
the north-south line. 

Determination of north-south line . — The first method is 
by the culmination of Delta Cassiopeia and Mizar; the 
second, by determining the hour angle and azimuth 
bearing of Polaris by observations on that star; and, 
third, the azimuth bearing between some terrestrial 
object and any definite celestial object. 

The culmination method is much the simplest of the 
three, requiring neither computation nor tables; it is 
necessary to know only the approximate time of culmina- 
tion. Plowever, during certain periods it will be incon- 
venient to determine the north-south line by the cul- 
mination method, due to clouds obscuring one or both 
constellations, or culmination occurring at a time when 
the sky is so well lighted that the stars can not be seen. 
Such conditions lead to the second and third methods, 
which are adapted for an}^ time at which Polaris or other 
celestial object selected for the observation may be seen. 
Both of the latter methods involve simple computation 
and the use of the American Ephemeris and Nautical 
Almanac. 

^luch care and attention should be given to adjust- 
ment and leveling of the instrument, determination of 
angles, and the disposition of decimals in computation. 
All angles should be read to the nearest hundredth of a 
degree. 

Whichever method is used, the theodolite must be in 
perfect adjustment and tlie actual point of observation 
selected and permanently marked. The observer’s 
watch will be coin])ared with the standard of time in 
local use, and corrections made as become necessary. 
The theodolite will b(^ placed centrally over the j)oint to 
b(' determined and the greatest care given to leveling. 

In eitlu'r th(! first or second method, it will be necessary 
to provide' a nu'ans of illuminating the cross hairs. Any 
meliiod whei’cby a beam of light can be rellected or 
thrown into the objeict end of telescope giving sullicient 
illumination to set foi'th the intc'rsection of ci'oss hairs 
and not flood the field with light to tlu^ extent that tho 
image' e)f the' star is lost will answer the purpe)se. 

hirst method. Delta ('assie)[)e'ia is the leeweu' left hanel 
star in the e-onstellation ('assieepeia, figure 43, when this 
e;e)nst('lhit ie)n is in the pe)sitie)n eef the lette'r W. During 
e'ulmination this star e'ro.sse's tiu' ne)rth-soiith line H) 
minutes in advance' of Be)laris and at the same time as 
Mizar, or the' middle' star in thee handle of Ih’sa Maje)r. 
d'he'se' two stars me'eitieuu'd are' eui e)p|)osite sieh's anel 
ne'arly e'e|uidistant freun Peelaris. Gulminatie)n e)f these 
twe) stars eece'urs twie-e' in 21 hours, and is fblh'we'd 
within 10 minute's by l^olaris crewsing the* same' merielian. 
d'lu'se facts, w'ith the aiel eef an instrument, afl'orel a 
simj)le me'ans e)f elete'rmining the' north-south lino. 


64 


INSTRUCTIONS FOR AEROLOGKWL OBSERVERS. 


Having determined the approximate time of culmina- 
tion of Delta Cassiopeia and Mizai', the theodolite is set 
over the exact point for whicli the meridian is to he deter- 
mined, plumbed, and leveled very carefully. It is well 
to do this while it is yet light. Be sure that the base 
plate is firmly locked and that both vertical and hori- 
zontal tangent screws can ])e turned freely without 
resistance. Sight tlie telescope upon some prominent 
point, as the tip of church spire, peak of gable roof, 
sharp corner of building, etc., and note the azimuth 
I’eading of this point on either the right or the 45-degree 
horizontal vernier. Take particular care that all subse- 


A 

♦ 



Fio. 43.— Constellations of Ursa Major and Cassiopeia. 

quent azimuth readings during this observation are made 
from the same horizontal vernier. A little time before 
culmination occurs, say half to three-quarters of an hour, 
a little practice should be gained by sighting upon the 
upper of the two stars and rapidly shifting the sight to 
the lower one. By the time culmination occurs, if the 
practice of raising and depressing telescope has been 
carried out, the observer will have gained considerable 
proficiency in the act, and the final movement at time of 
culmination will be performed with little or no difliculty. 

Have the cross hairs illuminated as mentioned above 
and the telescope properly focussed. Engage both verti- 


cal and horizontal tangent screws and bring the inter- 
section of the cross hairs centrally over the star in ques- 
tion. Quickly note the readings on the respective ver- 
niers and rapidly depress the telescope to elevation of 
the lower star by turning the vertical tangent screw, but 
do not disturb the horizontal tangent screw during the 
depression. The lower of the two stars will appear to the 
left of the vertical cross hair, but it will gradually approach 
the vertical hair as the time of culmination is approached. 
Raise the telescope to the upper of the two stars again, 
reset, read the angles from the same two verniers, and 
immediately depress the telescope as before. Repeat 
the foregoing operation until it is observed that the lower 
of the two stars also falls upon the vertical cross hair 
v/hen the telescope is depressed. When this is obtained, 
raise the telescope to the altitude position of Polaris, 
bvt do not disturh the azimuth setting, or the result of the 
observation will be of no avail. As a check, note that 
Polaris culminates just 10 minutes after the culmination 
of Delta Cassiopeia and Mizar. Note and record the 
azimutli setting, then depress the telescope to sight upon 
some conveniently accessible object where a distinct point 
coincident with the intersection of cross hairs will be 
placed. This point so placed will be true north. 

Example 1 : Suppose the theodolite is first sighted upon 
the cross of a church spire to the right of north, and the 
azimuth bearing, read from the right horizontal vernier, 
is 126.15 degrees. Let 98.4 degrees be the reading from 
the same vernier when Delta Cassiopeia and Mizar are in 
culmination. The difference between these two readings 
will give the angle at observation point between true 
north and the reference point, or the bearing of reference 
point from north: 126°. 15— 98°. 4 = 27°. 75; thus, when 
theodolite is set up with zero of base plate on north, the 
azimuth bearing of cross on church spire will be 27.75 
degrees. But, if the theodolite is set up with zero of 
base plate on south then the azimuth bearing of the 
church spire will be 180.0 degrees more, or 207°. 75. 

Second method. — Polaris, in its apparent counter- 
clockwise revolution about the pole, takes 23 hours 56.1 
minutes of our regular 24-hour day, thus culminating or 
crossing the meridian twice in 24 hours, and nearly 4 
minutes earlier each day. From this we sec that the 
position of Polaris east or west of the meridian for any 
specified time will vary from day to day. Knowing the 
correct local mean time and the time of up{)er culmination, 
the hour angle of Ptilaris (or the angle at the pole be- 
tween the north-south line and the hour eircle passing 
through Polaris), may be found. From the hour angle 
of Polaris, with the aid of the vVinerican E})hemeris and 
Nautical Almanac, the true azimuth of Polaris may be 
easily computed. The observations are made on Polaris 
at any convenient time after it beeomes visible. 

The theodolite is carefully set and leveled over the 
exact point of observation as in the preceding method, 
the cross hairs are likewise illuminated, and the watch 
compared with the correct local mean time. After the 


TNSTRUCTrONS FOR AER()L()(U(^AL OBSERVERS. 


05 


base plato is lockocl, the telescope is sighted U])()n some 
well-delined point as a reference mark, and the azimuth 
reading carefully noted and recorded. The telescope is 
then trained upon Polaris, and at the instant that the 
intersection of cross hairs is brought centrally over 
Polaris, the exact watch time to seconds is first noted, 
followed by the reading on the same azimutii vernier 
from which the azimuth reading of the reference point 
was made. All angles will be read to the nearest hun- 
dredth of a degree. A series of three or more observa- 
tions, 10 to lo minutes apart, should be taken as a check 
on the first and the computation as a whole. The final 
result of each computation should be no more than 0.02 
or 0.03 of a degree from the mean result. 

Example 2: On July 2, 1919, in lat. 42° 27' N., long. 
76° 29' W., or o h. 06 m. earlier than Greenwich, a series 
of three observations was made at 8 h. 42 m. 00 s., 8 h. 
55 m. 00 s., and 9 h. 10 m. 00 s., seventy-fifth meridian 
time. The base-plate reading of the right azimuth 
vernier, when sighted upon a definite point on the left of 
north, was 189.64 degi’ees. The azimuth readings from the 
same vernier when sighted upon Polaris during the obser- 
vations were 237°. 80, 237°. 89, and 237°. 98, respectively. 

Date, July 2, 1919. Position, lat. 42° 27' N., long. 
76° 29' W . — 5 h. 06 m. earlier than Greenwich. 



H. 

m. 

s. 

H. 

m. 

s. 

H. m. s. 

Time of observation (St. 75th). 
Earlier than seventy-fifth me- 

8 

42 

00 

8 

55 

00 

9 10 00 

ridian 


06 

00 


06 

00 

06 00 

Local mean time 

Reduction to sidereal time (A. 

8 

36 

00 

8 

49 

00 

9 04 00 

E. and N. A., Table III). . . 

+01 

25 

+01 

25 

+01 25 

Sidereal time mean noon 








Greenwich, or right ascen- 
ceneion of mean sun this 
date (A. E. and N. A., for 
Greenwich mean noon) 

0 

37 

54 

6 

37 

54 

6 37 54 

Correction for long., 5 h. OG m. 








00 8., (A. E. and N. A., Ta- 








ble HI) 

+00 

50 

+00 

50 

+00 50 

Lor al sidereal time 

Apparent right ascension of 

15 

16 

09 

15 

29 

09 

15 44 09 

Polaris tliis date (A. E. and 
N. A., apparent place of 
stars) 

1 

31 

34 

1 

31 

34 

1 31 34 

Hour angle of Polaris before 








upper culmination 

10 

15 

25 

10 

02 

25 

9 47 25 


if 


IJl. 

U 


lU. 

IJ. m. 

Same in detnmals of minutes. . . 

. 10 1.5.42 

10 02. 42 

9 47. 42 

Azimuth of Polaris at this hour 







angle and latitude (A. E. and 







N. A., Table JV) 


39. 58 


44. 23 

50.29 

Same reducr^l to degrees 



. 66 



. 74 

.84 

Observed azimuth of Polaris. . . 


237 

°. 80 


237 

°. 89 

237°. 98 

I'rue north on base plate 


237 

°. 14 


237' 

°. 15 

237°. 14 


Accepting 237°. 14 as the direction of true north when 
the theodolite is set with 189°. 64 on the reference point, 
the bearing or borizojital angle between the reference 
])oint and true north will be the dill'erence between 237°. I f 


and 189°. 64 or 47°. 50. Now, thou, with the zero of 
base-plate sotting on north, the azimuth bearing of the 
reference point is 360° minus 47°. 50, or 212°. 50. 

Third method. — 'Phe method of determining the north- 
south meridian by observation on the sun necessitates 
the use of a ray filter or smoked glass placed over the 
eyepiece during the observation. In the absence of both, 
the observer may wear smoked glasses or if these are not 
at hand, an image of the sun may be cast on a piece of 
white paper held at a distance from the eyepiece. By 
adjusting the focus the shadow of cross hairs will be seen 
on the paper and thus facilitate proper centering over 
the sun. Do not leave the object lens of the telescope 
exposed to the direct rays of the sun for any length of 
time. Such continued exposure is likely to render the 
lens unfit for use, as already explained. 

The preparation and setting of theodolite for this 
method is essentially the same as for the other two 
methods mentioned above, namely, properly place, 
level, and check the theodolite, lock base-plate, estab- 
lish reference point, and note the actual time of observa- 
tion. By the following method of computation, the 
north-south line may be determined from observations 
upon any Imown celestial body, it bemg only necessary 
to substitute the other definitely known body for the 
sun. However, the sun afi'ords the most convenient 
object for the determination. The factors resolve 
themselves into a spherical triangle, which may be com- 
puted by the following formulie : 

Let S = i (polar distance + co-latitude) , p + co-lat. ; 

Let D = i (polar distance — co-latitude) , p — co-lat. 

Let it = i hour angle ; 

Let Z = true azimuth ; 

'I'hen tan X = sin D cosec N cot ht 
tan Y = cos V sec S cot Y 
and' Z = X +Y, or X — 1'. 

Example 3: On June 19, 1920, in latitude 38° 54' 
12" N., longitude 77° 03' 03" W., or 5 h. 08 m. 12 s. 
earlier than Greenwich, observations were made on the 
sun at 1 h. 36 m. 44 s., seventy-fifth meridian time. 

The baseplate readinj' of the right azimuth vernier when 


sighteil upon reference point to tlie left of sun was. . . . 1-12°. 28 

Observed azimuth reading of sun, same vernier 231)°. 78 

Azimuth difference of points 97°. 50 

U. m, s. 

Time of observation, seventy-fifth meridian 1 3(i 44 

Karlier than seventy-fifth meridian time 08 12 

Local mean time of obscr . ation 1 28 32 

liquation of time (apparent — mean, A. IC. and N. A.) —01 04 

Local ajrparent time 1 27 28 

Hour angle of sun (0 1 27 28 

it 43 44 

'I'he same converted to degrees 10° .50' 00" 


> If 6’ Is IMS than 90 degrees, and (a) polar distance greater than co-lat., use sum of ,Y 
and Y; (6) polar distance less than co-lat., use dillorence of X and 1'. 

If .9 is greater than 90 degrees, always u.sc diflorcnce of X and Y, which, subtracted 
from ItO degrees, results in the true azimuth. 

’ .Since 15‘’»»oiio h jiir in time, the liour angle may be cunvcrlod to degrees by using 
l.'i as a factor, and reducing the whole to the simplest form in degrees, minutes, and 
seconds. 


46320 21- - f) 


66 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 


H. m. s. 

co-lat. (90° — latitude of station) 51° 06' 00" 

Polar distance of sun (90° — declination) 66° 34' 00" 

/) + co-lat 117° 40' 00" 

S, or ^ (7)+ co-lat.) 58° 50' 00" 

p - co-lat 15° 28' 00'/ 

77, ori0;-co-lat.) 7° 44' 00" 


^t=10° 56' 00" log cot it=0. 71405 log cot ^f=0. 7140S 

-5=58° 50' 00" log cosec 5=0. 06770 log sec 5=0. 28607 

D= 7° 44' 00" log sin Z)=9. 12892 log cos D=9. 99603 

log tan X= 9. 91067 log tan y=0. 99615 


X=39° 08' 55" F=84° 14' 20" 

X+Y=123° 23' 15", or 123°.39 

True bearing of sun from north tlu-ougb west 123°. 39 

Azimuth difference 97°. 50 

Bearing of reference point from north through west 220°. 89 


True bearing of reference point from north, 360° — 220°. 89, or 139.11 
degrees. 

Whenever it is possible all computations should be 
made before the theodolite is disturbed or moved from 
its setting. When the true north-south line has been 
determined, the true bearing of reference point from ob- 
servation point with at least two others at different dis- 
tances should be determined. These points with their 
bearings from north or south will constitute the orienta- 
tion points of the station. A plan of these points will be 
constructed to some convenient scale on a card 4 inches 
by 6 inches and mailed to Central Office for file, along 
with a brief description of the arrangement of equip- 
ment. At double-theodolite stations, a second card will 
show the length, bearing, and arrangement of base lines. 

Orientation of theodolite . — In single theodolite work, 
zero of the base plate wdll be set on north, for when the 
data are plotted upon the regular single-theodolite 
plotting board, the wind directions are more easily 
determined than otherwise. Further explanation will 
be given in later sections. 

For double- theodolite work, the setting of zero on the 
base plate may vary with the different methods used in 
plotting the data obtained. In any event both instru- 
ments should be homologously oriented, that is, the 
zeros of the base plates of both instruments on tlie same 
geographic point. Three methods of double-tlicodolite 
orientation are accepted. Namely, base-line orienta- 
tion, north orientation, and south orientation. In all 
methods of plotting, base-line orientation is preferred, 
wherein the theodolite at primary station is set with 
zero of base plate on the base line, or secondar}^ station, 
and the theodolite at the secondary station is set with 
180° on base line or primary station. In north orienta- 
tion and south orientation, both theodolites are set 
with the zero of base plate on north and south respec- 
tively. These latter methods are well adapted for the 
graphical method of two-theodolite plotting, but in- 
volve azimuth corrections equal to the base-line bear- 
ing with north-south line, when tlie slide-rule method is 
used, d'lie same exception holds for logarithms. There- 
fore when the flight is to be computed by slide ride or 
jogs and then plotted, orientation b}^ the base line 
method should be adopted. 


3. B.\LLOONS. 

The balloons in use for pilot balloon work are made 
from the best grades of raw gum rubber to be obtained. 
They are manufactured by the "dip” process, and are 
thei'efore without seams and nearly spherical in shape. 
An extension of the longer axis abou t 2 inches in length 
and Ft inches in diameter, terminating in a rolled edge, 
forms the neck or appendix througli which inflation is 
accomplished. Balloons of two sizes are used, the first, 
6 inches in diameter when uninfiated, for single-theodo- 
lite work, and the second, 9 inches in diameter uninfiated, 
for special double-theodolite work. Both sizes of bal- 
loons may be j)rocured either uncolored or colored. 

. Color . — The uncolored balloons are those of natural 
gum, appearing to be a light tan or pale gray, while the 
colored may be either Vermillion, maroon, blue, or pur- 
ple. The color of balloons when inflated is much less 
intense, and frequenth’ of different color, than when un- 
inflated. As a whole, the appearance of balloons when 
at full inflation ma}’ be classed as transparent, translu- 
cent, or opaque. Balloons colored with a pigment in 
the body of the rubber are likely to be opaque when 
inflated, and those colored by a stain will be opaque only 
when colored Avith a dense stain, and eA^en then are more 
likely to belong to the translucent class. The uncol- 
ored balloon becomes transparent under ordinary con- 
ditions of inflation. 

If the sky AA'erc of one color continuously, it would be 
necessary to have but one color of balloon for ail times. 
That color Avould be one which would present a strong 
contrast AAuth the color of the sky. Since the sky color- 
ing may be either blue, AA'hite, or gray, the balloons most 
easily seen Avith the aid of the theodolite AAnll necessai’ily 
be those AAdiich present the strongest contrast to these 
sky colors. In general, the strongest contrast of colors 
is that of black and A\diite. Next in order come the asso- 
ciation, or juxtaposition, (1) of two primary colors, (2) of 
one primary and one complementary secondary, and 
(3) of a light tint of one primary and a dark shade of the 
same or another primary, the strength of contrast de- 
creasing in the order giAmn. If Ave let the primary colors 
be red, blue, and yelloAAq the secondaries pairs of prima- 
ries combined in eijual Auilumes, and a complementaiy 
secondary to a primary be a secondary composed of two 
other primaries, then the above scheme of contrasts 
used by the United States Coast and Geodetic SuiA’oy is 
represented by the following table: 


For color contrasts, juxtapose. 


(1) 

I’rnnary with other primary. 

(2) 

I’riniary with coniplomcii- 
ta'ry secondary. 

(3) 

I.,iyht tint of irriinary with 
dark shade of same or 
other primary. 

Red with — 

Ited with— 

Light red with— 

Blue or yellow. 

Blue and yellow or 

Dark red, dm ! blue, or 
dark yellow. 

green. 

JAlue with — 

Bine with— 

Light blue with— 

Rod or yellow. 

lied and yellow or 

Dark blue, dark yellow. 

orange. 

or dark red. 

Yellow with — 

A’cllow with — 

Light yellow with— 

Rod or bine. 

Rod and bine or violet. 

Dark yellow, dark red, 
or dark blue. 


INSTRUCTIONS FOR AFROLOOK^AL OBSFRVERS. 


07 


From tlio above wo see that the strongest (jontrast 
formed against a blue sky would bo obtained by using 
a red or a yellow balloon, and a strong contrast, though 
less marked, would be obtained by the use of an orange- 
colored balloon. When the sky is a light blue or fading 
into white and linally becoming gray, a strong contrast 
is obtained by the use of dark shades of blue, yellow, or 
red. The same relative principles v/ould hold if the 
sky coloring were red or yellow instead of blue. Since 
these colors but rarely exist at the times of balloon 
observation, and even then in but the lightest of tints, 
we may confine our interest to the method of contrasts 
by (3). The application is similar to and essentially 
the same as for light blue. 

Cloudiness, haze, or mist is nearly always associated 
with the sky colors. Tints of red, blue, and yellow, in 
the majority of cases, fade into the whites or gradually 
deepen into the grays so common during cloudiness. 
But these conditions of sky coloring, we learn from the 
above table, are most strongly contrasted by the use of 
dark red, blue, or yellow. Experience has shown that 
dark-red balloons, or even light red, if the coloring has 
rendered the balloons opaque, are best adapted for ah 
round use whether the sky be blue, white, or gray. When 
the sky is cloudless and well tinted with blue, remark- 
able results may be gained by the use of an uncolored 
or gray balloon. But this is nothing more than a reversal 
of contrast by (3) method. However, the successful 
use of the uncolored balloon is measured by the degree 
of clearness, the absence of haze and mist, and the 
predominance of bright sunlight throughout the flight, 
for the uncolored balloon against a white or gray back- 
ground readily blends and becomes invisible. In l)right 
sunlight, the uncolored balloon possesses the main 
properties of a mirror, for the light upon it from the 
sun is reflected to the observer so long as the balloon 
does not come directly between the ol)server and the 
sun. If the latter condition obtains, the light then 
passes through the balloon, rendering it invisible. 

On days of few anti very light clouds a balloon of 
translucent coloring may be used with equal succe.ss; 
but on days with appreciable cloudiness or haze a 
balloon of opatjue coloring must be used to obtain the 
best results. In general — 

Uncolored balloons will be used upon clear days, or when there is an 
assurance that the sun will shine on the balloon throughout the flight, 
and 

Colored b'dloons will be used upon days when clouds, haze, or mist 
cause the sky to present a white or grayish appearance. 

Occasions will arise when the supjtly of colored balloons 
will become exhausted, and a satisfactory run can not 
be made without one. One of the uticolored ty])e may 
then be satisfactorily colored by the following method; 

The materials needed are some raw linseed oil and a 
small quantity of printer’s ink. It is well to have two 
or three colors such as red, blue or black, and yellow. 
Add suflicient linseed oil to each can of ink to make a 


thick syrup or paste. There will be little difliculty in 
this since the ink is .so readily soluble in the oil. To 
color the balloon succe.ssfully and conveniently, and 
without damage to the clothing, rc([uires a little special 
manipulation, which is accomplished as follows: Place 
the thumbs of each hand within the neck of the balloon 
and allow the fingers to extend down the outside. 
Slightly distend the neck and bend the extended fingers 
in toward the palm of the hand at the same time pushing 
the walls of the balloon up to the region of the neck. 
Then by exerting a double kneading movement, by rolling 
the back of the hands over each other, the walls of the 
balloon will be passed through the small passage of the 
neck, exposing the greater portion of the interior surface 
of the balloon. However, the balloon is not to be turned 
inside out completely, but the apex is left protruding from 
the underside, sufficiently to allow a finger hold for turn- 
ing the balloon back to the initial position. The balloon 
thus prepared will appear with the greater portion of the 
interior surface exposed above and outside the neck, and 
forming a depression at the point where it passes through 
the appendix of the balloon to the remaining portion of 
the unturned balloon on the underside of the hand. Now, 
in this depression, place a small quantity of the ink and 
oil mixture to the amount of about 2 or 3 grams. After 
the ink has been so placed, turn the balloon to the initial 
position by pulling on the lower protruding portion. 
This will close the surplus walls of the balloon over the 
ink mixture, thus preventing it from coming in contact 
with the neck or exterior surface of the balloon. When 
completely turned, proceed with the kneading until the 
color is evenly distributed. The kneading is quite de- 
sirable in itself and provides for maximum inflation of 
balloon, as will be explained later. 

Patcldmi leahj ballootis . — Occasionally balloons, when 
received from the manufacturers, will l)c found to iiave 
.small “ pinholes.” In some cases such holes may develop 
during inflation duo to small “air hubbies” or other 
defects. Tiiese defective l)alloons sboidd not be dis- 
carded, but can and should be patclu'd and made ready 
for use by the following method: 

Procure a piece of very fine emery paper, an ounce or 
two of benzine, a small tube of Goodyear rubber cement, 
and a piece of a previously burst balloon. Turn the 
defective balloon inside out and lay it U{)on a ffat surface, 
with the portion to be patched uppermost. Slightly 
roughen the rubber around the pinhole, also the piece of 
“patch” rubber, with the emery papei-, wash each with a 
little benzine, and then ap{)ly to each a thin layer of 
the cememt. ’Flie cc-nient slioiild be allowe<l to firy for 
about live minutes, when anotiier layer should be applied. 
Place the patch on the prepared surface of the balloon, 
press it firmly down and then lay a small weight upon it, 
in order to insure even and complete coherence. The 
balloon should remain thus for 12 to 21 hours, after 
which it is turned back so that the patch is on the inside, 
ff'he balloon is now reaily for use, but should not be 


68 


INSTEUCTIONS FOE AEEOLOGICAL OBSEEVEES. 


inflated to give a rate of ascent greater than 180 m/m 
(preferably 160). During inflation the patch should be 
closely watched; if it curls up at the edges appreciably, 
tlie balloon should be laid aside and the patch later 
rcceniented. 

Tiie size of the patch to be used will vary somewhat 
with tlie size of the hole, but in general a tliameter of D 
(o 2 inches is recommended. 

Experience has shown that it is well to inspect each 
lot of balloons as soon as received and to patch all defec- 
tive ones at one time. 

Size . — At present the balloons in use for pilot balloon 
work are 6 and 9 inches in diameter uninflated. In prac- 
ticall}'' all single-theodolite observations 6-inch balloons 
will be used, while the 9-inch will be reserved for double 
theodolite work. The 9-inch are sometimes used in single- 
theodolite work when it is observed that an extremely 
high wind velocit}^ obtains either aloft or at the surface. 
But a 6-inch balloon filled to a high ascensional rate is 
recommended in preference to a 9-inch for single-theodo- 
lite work. In double-theodolite work either 6-inch or 
9-inch balloons may be used, depending upon the sky 
conditions at the time of observation. On hazy days or 
when low clouds predominate, or when the velocities at 
the surface and lower levels are low, 6-inch balloons 
should be used, thus leaving the 9-inch for days when 
there is an assurance of a fairly long flight. 

Weighing. — The weight of the empty balloon varies 
widely for both the 6-inch and the 9-inch sizes. The 
weighit of the 6-inch will range from 15 grams to 50 grams, 
with a mean weight of about 25 grams, while the 9-inch will 
range from 30 grams to 75 grams, with a mean weight 
around 52 grams. In determining the weight of a bal- 
loon, a balance like that shown in figure 44 is used, aiul 
the accuracy is carried to the nearest whole gram. 
Before weighing the balloon, it is noted that the beam of 
the balance is in true equilibrium when both, pans are free 
from load and the rider is in position at the zero point 
on the scale. The balloon is then folded two or three times 
along the major axis to form a long narroAV strip, which 
is then firmly rolled into a ball, commencing at the apeX 
of f)alloon, that all air may be expelled through the neck 
in the process of rolling. If the balloon is prej)ared in 
this manner, the weight obtained will for the most part 
be the actual weight of the empty envelope. If a filling 
apparatus such as that shown in figure 41 is used, the 
procedure v/ill vary but little. Kquilibrium will be estab- 
lished as with the free balance, the balloon likewise rolled 
and expelled of air, will be placed over the nozzle and 
weiglied to the nearest whole gram. 

Inflation . — Inflation may be classed as "indefinite” 
and "definite.” By indefinite inflation the balloon is 
filled to a convenient size, and the resulting ascensional 
rate interjiolated from Table 26 (section 8), or computed 
from the formula. First, the balloon is selected as to 
size and color, then it is vigorously worked and kneaded 
in the hands until it becomes warm and flexible. Stretch- 


ing and kneading it well before attaching it to the nozzle 
eliminate much bursting during inflation. A mild 
kneading is not sufficient; it should be pulled and 
stretched until there is a sensibility of heat when pulled 
over the hands. The balloon is then carefully folded, 
rolled, and weighed on a free balance as described above. 
With the balloon still rolled tightly, it is placed in the 
palm of the hand with about or 2 inches of the neck 
free and protruding from between the fingers and thumb. 
It is then brought near the nozzle of the fdler pipe where 
it is held until the gas has been turned on at the hydrogen 
tank. A quick spurt of the gas will drive the air from 
the tube and this operation is quickly followed by the 
placing of the balloon over the nozzle. Thus the system 
is practically free of air and gas. The balloon is then 
securely wrapped and tied to the nozzle with tape and 
the gas is allowed to enter the balloon, slowly at first, 
until the rubber begins to stretch in all directions when 
the flow may be increased and carried to full inflation. 
Full inflation should not be accomplished in less than 40 
to 50 seconds. Much of the bursting during inflation is 
due to too rapid filling. The size to which inflation can 
be carried will depend upon the convenience of the sta- 
tion, that is, the size of passages and openings through 
which the inflated balloon must be transported to the 
free air. Balloons should always be inflated inside a 
building or in a place well sheltered from drafts and cur- 
rents. The presence of these disturbances, though small 
in themselves, materially affects the ascensional rate of 
the balloon. It is necessary that this rate of ascent be 
ineasured in still air, free from such gusts. Since the 
filling will be done inside, the width or size of the open- 
ing through which the balloon must be passed to the free 
air will generally limit the diameters of the inflated bal- 
loon. An opening 29 inches wide, the average width of 
a common door, is equivalent to about 74 cm. and the 
balloon to be passed through this opening should not be 
inflated much beyond this diameter, for compression of 
the balloon to allow passage, and contact with the sharp 
edges and corners of casings will often result in the 
puncture of an inflated balloon. 

(Much care must be given to the handling of the iiw 
llated balloon until it is released, for the tightly stretched 
rubber becomes quite delicate and is easily punctured 
by contact with relatively blunt corners or rough sur- 
faces. For this reason it is best to set the movable arm 
of the calipers at the width of the smallest opening 
through which a successful passage must be made, and 
then (ill the balloon to that diameter, fiflius, for an open- 
ing of 74 cm. in width, the calipers should be set for not 
more than 75 cm., and as the inllated balloon approaches 
this diameter, place the calijiers in a horizontal position 
about the balloon so that one arm of the calipei's is in 
contact with the surface of the balloon. As the increasing 
size of the balloon reaches the setting ol the calipers, 
shut off the gas by <dosing the valve on the hydrogeti 
taidv. 


INSTRUCTIONS FOR y\ KROLOCK'AL OBSERVERS. 


69 


Sealimj . — The balloon is now ready to bo sealed and 
this is accomplished in the following manner: Prepare 
two No. 16 rubber bands for the tie, by placing them 
together over the lingers. The two bands are then given 
a half twist and doubled over to make a 4-stranded 
ring or loop. With a finger of each hand in this 4- 
stranded loop, the bands are slightly stretched and the 
fingers meanwhile twirled a few times so that the strands 
of the loop may be made even in tension, or the stress on 
the various strands equalized. The bands will now un- 
dergo considerable stress before any one of the strands 
will break. When this is completed the tie so prepared 
is slipped half way over the thumb and fingers of one 
hand, leaving the other entirely free. To apply the tie 
to the balloon, firmly grasp the neck of the balloon with 
the free hand about the nozzle and untie the tape. 
Place the other hand on the under side of the balloon 
vuth palm upward and fingers extended to form a shallow 
cup, and while the inflated balloon is held on the nozzle, 
it is raised or stretched vertically at the neck, and turned 
about until the neck is twisted upon itself. Care should 
be exercised that long or sharp finger nails do not punc- 
ture the balloon. By lessening the grip upon the nozzle, 
the balloon is allowed to slip therefrom and the neck is 
twisted further to insure a close hard roll or stem. With 
the free hand the band prepared for sealing is removed 
from about the fingers and slipped over the twisted por- 
tion of the neck where it is tightly wrapped by a series 
of alternating half twists and loopings accompanied by 
a firm tension on the bands to insure a tight joint. The 
balloon is now inflated and, if the foregoing directions 
have been closely followed, is properly sealed. The next 
procedure is to measure the free lift or the mass in whole 
grams which the inflated balloon will just lift from a 
horizontal plane. 

The free lift of a balloon is measured by attaching it to 
the left-hand pan of the free balance and placing weights 
thereon sufficient to bring the beam system of balance 
into equilibrium. In the event that the balloon can not 
be attached to the scale pan, it may bo attached to a 
200-gram, or any other known weight greater than the free 
lift, by means of a rubber band looped at each end as a slip 
noose. One end of the band is drawn over the neck of 
the balloon and the other is drawn ovei‘ the knob of the 
weight. A weight of 200 grams will ordinarily be 
greater than the free lift of the balloons inflated to a 
maximum diameter of 74 cm. When the free lift is 
greater than 200 grams, the balloon may bo attached to 
a larger weight. The weight with the balloon attached 
is then placed on the left-hand j)an of the free balance 
which it will depress to the stop. Smaller weights are 
then applied to the right-hand pan of Iho balance until 
equilibrium of the beam .system is reestablished. The 
difforonce between this weight and that to which the 
balloon is attached will give the free lift of the balloon. 
As an example, suppose the weight attached is a 200- 
gram weight, and the weight applied to the opposite 


side of the free balance amounts to 10 grams, then the 
free lift (1) is equal to 200 grams — 19 grams or 181 grams. 

With the weight of the balloon (w), and the amount 
of the free lift (1), as factors, the ascensional rate of the 
inflated balloon is computed from the formula: 


V~72(ly,or 

(1) 

F=72(^,)-”* 

(2) 


wherein F= ascensional rate, or vertical velocity of 
balloon, 

Z = the free lift, representing the actual lifting 
force in grams, of the inflated balloon, 

L = the total lift, or the free lift plus the weight 
of the balloon expelled of air. 

Formula (1) may be further simplified to the following 
working form, without alteration of the resulting values: 

F= 72 (log Z - 1 log Z) -^25 (3) 

Example: Let the weight (w) be 29 grams, and the 
free lift (Z) be 181 grams, then the total lift (L), will be 
w + 1, or 210 grams (29 grams 4- 181 grams = 210 grams). 
Substituting these values in formula (3) and solving, 
we have: 

log Z = 2. 2.5768 
-log Z = 2. 32222 X § = 1. 54815 

0. 70953 X . 625 =log 0. 44346 = 
antilog 2. 7762 X 72 = 199. 89 

Thus the ascensional rate for the balloon inflated under 
these conditions is 200 meters per minute. This opera- 
tion is greatly simplified by referring to table 26 (sec- 
tion 8), in which the ascensional rate may bo found at 
the intersection of weight column and free-lift line. 
Reference to table 27 (section 8), “Altitude time-tables 
for various rates of ascent,” for the ascensional rates 
found will give the height of the balloon for the end of 
any particular minute during which the balloon may bo 
in the air. In this table it will be observed that the 
values for the first five minutes do not increase regularly 
by multiples of the ascensional rates given in the head- 
ings of the columns, but that they are in each case 
slightly larger than the values indicated by those rates. 
Those increased values have been obtained by applying 
certain additive corrections, viz., 20 per cent for the first 
minute, 10 per cent for each of the second and third 
minutes, and 5 per cent for each of the fourth and fifth 
minutes. For a discussion of the necessity of applying 
these corrections, sec paper by Capt. B. J. Sherry on 
“The Rato of Ascent of Pilot Ilalloons,” Moxtiii.y 
WK. vniKn Rkview, Docombor, 1920, pp. 692-694. In 
case any ascensional rate is used other than those given 
in table 27, it will be necessary to apply the additive 
corrections at the time of observation. The computed 
altitude of the balloon at the end of the first minute will 
then bo 120 per cent of the ascensional rate; at the end 


70 


INSTKUCTIONS FOK AEROLOGTCAL OBSERVERS. 


of the second minnte it will be this value plus 110 per cent 
of the ascensional rate; and so on. To eliminate this 
inconvenience it is urged that the “definite inflation” 
method be employed whenever possible. 

Measurinej . — Two diameters of the balloon are then 
measured ; The vertical diameter or that along the major 
axis from the neck to the apex; and the horizontal diam- 
eter, or that in a plane perpendicular to the vertical 
diameter. In making these measurements of balloon 
diameters, -wnth the balloon calipers, it has been found 
best to lay the calipers alongside the balloon with the 
graduated bar about parallel with the diameter to be 
measured, and the arms well opened and extending to 
one side disengaging the balloon. Upon the bar as an 
axis, turn the calipers to engage the balloon at the great- 
est width and move the sliding arm until the opening 
between the two arms just contains the balloon. The 
reading on the main bar at inside edge of the movable 
arm will be the desired diameter in centimeters. Manipu- 
lation of the calipers after this fashion will eliminate much 
of the bursting during inflation. The balloon is now 
ready for release. 

By “definite inflation,” the ascensional rate to be used 
is decided upon, and the balloon inflated to meet those 
requirements. Inflation of this nature can be accom- 
plished only with the aid of some filling apparatus, which 
should be sufficiently sensitive to register the weight of the 
balloon and the free lift to the nearest whole gram. 
Figure 44 shovrs a simple arrangement of such apparatus 
and works very well when carefully assembled. The 
balance regularly supplied for balloon work is fitted up 
as follows : A wooden nozzle, N, figure 44, about 2 inches 
long bj* 2 inches in diameter, is turned from a piece of 
compact wood. The circular surface is corrugated in 
rings about one-fourth inch apart, which will assist in 
retaining the neck of the balloon and generally (diminate 
the need for tying. Through the center of the cylindrical 
block is bored a hole sufficiently large to receive the end 
of an elbow or right-angle bend of piping. This com- 
pleted nozzle is securely fastened to the right-liand side 
of the balance, centrally over the pan, and with the free 
end of the elbow extending in a horizontal direction and 
perpendicular to the line of the beam system. A piece 
of lead tubing, T, about 20 to 24 inches in length, is passed 
through the round bole in the base of the halance and 
thence between the scale bar and fulcrum support until 
about 6 inches of tubing extend above this point. Note 
that there is sufficient space between the Icatl tubing and 
scale bar to allow the passage of rider on the scale bar. 
This will necessitate the bending and slight flattening 
of the tubing at that point. When the lead tubing is all 
placed, the set screw in the base of halance is turned in 
to hold the tubing in place, and the remainder of the 
tubing extending belov/ the base is bent at right angles 
to pass out at the back of the balance. 

A short length of I'ubber tubing is here attached to 
connect the lead tubing with a three-way stopcock, C. 


The remainder of hydrogen line, L, is identical with that 
supplied for indefinite inflation. About 2 inches of the 
lead tubing extending above the balance is bent through 
a right-angle bend toward the front of the balance or in 
the same general direction as that of the free end of 
nozzle elbow, N, and the two ends connected mth a rub- 
ber U-tube, U, of very light flexible material. Tare, or 
counterweight, W, is then added to the left-hand pan of 
the balance to bring the beam system into eqiiilibrium, 
and the apparatus is then complete. 

The procedure for definite inflation is as follows: 
Decide upon the rate of ascent to be used, 160, 180, or 
200, etc., meters per minute. Table 28 (sec. 8) ; see 
that filling apparatus is in equilibrium; select color and 
size of balloon, knead, fold, roll, and weigh as above 
stated. While still firmly rolled, stretch the neck of the 
balloon over the filler nozzle in a manner similar to that 
described under indefinite inflation, and turn on the gas 
slowly. In some instances it will be necessary to tie the 
balloon on the nozzle, in which case the string is placed 
on the nozzle side of the balance and the whole system 
adjusted for equilibrium before the balloon is weighed. 
While the balloon is being filled, determine the amount 
of free lift to be given to it by referring to Table 28, under 
the column head of selected ascensional rate and opposite 
to the weight of the balloon. 

As an example, suppose the ascensional rate selected is 
200 m/m, and the weight of the balloon is 34 grams. 
Then in Table 28, under 200 and oppo.site 34, it is found 
that the necessary free lift to which this particular balloon 
must be inflated is 188.0 grams. Had the ending of free 
lift been in tenths of grams, it would have been reduced to 
nearest whole grams. Weights equivalent to that mass 
arc placed on the pan of balance under the balloon. This 
end of the beam system will then be depressed to the stop. 
When sufficient gas has been admitted to raise the beam 
system to the point of equilibrium the valve at the tank 
is closed. The final adjustment is made by means of the 
three-way stopcock. Generali}^ the balloon is filled to a 
point just beyond e(iuilibrium and the surplus of gas 
allowed to escape through the three-way cock. AVhen 
the balance is brought to equilibrium under these condi- 
tions this particular balloon is properly inflated to give an 
ascensional rate of 200 m/m. It is now sealed and 
measured as in indefinite inflation. 

If the foregoing instructions have been closely fol- 
lowed, everything is in readiness for an actual observation. 

Caution . — Never allow the presence of lighted cigars, 
pipes, cigarettes, lamps, or lanterns in or near the build- 
ings during the process of inflation, llydrogcji gas when 
mixed with the air in correct proportions forms a A'ciy 
powerful explosive. Even glowing coals and cinders are 
sufficient to ignite the gas. 

4. MAKING AN OllSKRVATION. 

Regularly, at all stations unless otherwise sj)ecilied, 
observations will bo taken at 8 a. m. atul 4 p. m., seventy- 



Ki(i. M. Mullooii-fillinK appanitus used for '‘defiiiito” inflation ( r, ihreeway stopcock; A, liydroKci 
line; iV, filler nozzle; 7', lead Inhin^'; (J, rul)l>er U-lube; II', counterweight). 



INSTRUCTIONS FOR AEROr.OGlCAL OBSERVERS. 


71 


fifth meridian time. Occasionally special observations 
will be requested, and those will be made at the times indi- 
cated. But whether morning, evening, or special, the 
procedure will be identically the same. Not all stations 
will telegraph both morning and evening observations, 
but each station will bo instructetl separately with respect 
to the observations that are to be telegraphed. 

A pilot-balloon observation may be divided into three 
parts, (1) collection of data, (2) computation and plot- 
ting, and (3) reduction and tabulation. 

The first part, the collection of data, is the making of 
the observation itself, and involves the taking and the 
recording of balloon data, meteorological data, and ob- 
served readings of azimuth and elevation angles. 

Computation and plotting, the second part, is a con- 
necting link between (1) and (3). It includes the work 
necessary to prepare the observed data for reduction and 
tabulation. There are various methods by which this 
may be accomplished, viz., the slide-rule method; the 
graphical method, and the logarithmic method. 

The last part (3), covers the major portion of the work 
connected with the average pilot-balloon observation, 
namely, plotting the flight, determining the direction and 
velocity at the end of each minute, plotting the velocity- 
azimuth graph, and reading oft' and tabulating the values 
for the specified levels. 

The single-theodolite observation requires the services 
of two men, the observer and the recorder. The mate- 
rials necessary are the theodolite, balloons, balance and 
weights, supply of hydrogen, tape or string, rubber 
bands, measuring calipers, watch or timing apparatus, 
slide rule, plotting board, graphing board, clip board, 
ascensional rate tables, conversion tables, forms, art 
gum, and pencils, both hard and soft. 

The observer is responsible for the setting of the theodo- 
lite, and the orientation on north or south, the meteor- 
ological data, and the proper placement of cross hairs 
over the balloon during the observation. The recorder 
is responsible for the preparation of the balloon, reading 
of angles at theodolite, rccoi-ding of all data on Form 
No. 1110-Aer., Table 19, and the computations so far as 
possible during the observation. 

The theodolite, balloons, balance, and weights have 
been already discussed. The hydrogen used for inflation 
is supplied, under considerable [)ressure, in strong steel 
cylinders. These cylinders when charged should be 
stored in a cool or at least well-shaded place, and entirely 
free from exposure to flame or glowing coals and embers. 
The watch is generally used for marking the time, though 
there are a few cases in w'hich an idle “triple register” 
clock has been arranged as a time-interval clock. The slide 
rule, plotting board, etc., will bo discusse.d in their turn. 

To arrange the time-interval clock as mentioned above, 
run a wire tlirough the binding post of both wind direc- 
tion and sunshine brush and thence to the battery. 
From there it is carried to the place of observation/ ^ 
where it is connected to a buzzer, or bell, and passed* 


through a switch, thence back to the ground post of the 
clock. By this arrangement the clock will give a double 
signal at the end of each minute. The signals, or the 
two buzzes, will be about five seconds apart. It should 
be so arranged that the first buzz will be a little long 
and quite loud, and the second buzz much shorter and 
as definitely short as can be successfully arranged. The 
first buzz will be knov/n as the “warning” signal and 
the second buzz as the “read” signal. This “warning” 
signal will give ample time for the observer to center 
the balloon and the recorder to prepare for the reading 
of the angles. Without the interval clock it will be 
necessary to keep close watch of the time, in w’hich case 
the “warning” signal will be called by the recorder 
about five seconds before the expiration of the minute, 
or the “read,” signal. Generally the balloon is released 
on the full minute, therefore the “read” signal would 
occur at the sixtieth second and the “warning” signal 
on the fifty-fifth second. 

Since the observer is enthely responsible for the data 
obtained by theodolite when the angles are carefully 
and accurately read, he will set up the instrument over 
the observation point, level, and orient as described in 
earlier paragraphs under “The Theodolite,” section 2. 
Suppose this setting to be with an elevation angle of 1 °.3 and 
the azimuth angle of the 45° horizontal vernier to be 345°. 6 
with zero of the base plate on north. (See Table 19.) 

After setting of the theodolite is completed, the oi) 
server will note and record the current meteorological 
data comprising the amount, kind, and direction of 
movement of the clouds, the direction and velocity of 
movement of the surface wind, the current temperature 
and the wet bulb temperature, the pressure, and the rela- 
tive humidity. Where a x’egular meteorological observa- 
tion has been taken within 15 minutes of the actual start- 
ing time of the balloon ascension (time of balloon release) 
that meteorological observation may be used instead of 
taking another. But in the event that a period of more 
than 15 minutes of time has elapsed, a separate and com- 
plete meteorological observation will bo made. The 
results of this meteorological observation and the settings 
of the theodolite will be entered in the respective spaces 
upon the work sheet, or Form No. 1110-Aer. 

In the meantime the recorder will select the size and 
color of balloon to be used, weigh, inllate, and measure 
the free lift and ascertain the ascensional rate as in- 
structed under “Inllation, ” section 3. Suppose the 
balloon selected is a 0-inch red, and it is to be given a 
delinito inllation to attain an ascensional rate of 200 m/m. 
The weight of the balloon is found to be 38 grams. 
When referring to Talfie 28, wo find that a free lift of 
193.1 grams is rexiuired to give the inllated balloon an 
upward velocity of 200 m/m. Since the free lift of inlla- 
tion is measured only in whole grams, this will bo re- 
duced to 193 grams and balloon inflated to that point. 
All of these data will bo recorded in the proper spaces on 
jForm No. 1110-Aer. as soon as they are determined. 


72 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


[Form No, lllO-Aor.) 


Station (place of observation). 
A, '■cension number, 2136. 


Table 19. 

V. S. DEPARTMENT OP AGRICULTURE, WEATHER BUREAU. 

Pilot Balloon Ascension Report. 

Date, July 10, 1920. 

Number of theodolites used, 1. 


Starting time, 8:26 a. m. 
75th meridian time, 


Observation point, A. Altitude, 55.3 m. 


Observation point. 


Altitude, m. 


8. 

9. 

10 . 

11 . 

12 . 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20 . 

21 . 

22 . 


Minute. 

Elevation 

angle. 

Azimuth 

angle. 

Distanee 
from 
ohserva- 
tion point. 

m. 

Altitude. 

m. 

Wind 

direction. 

Wind 

velocity. 

m.. p. s. 


1.3 

345.6 

Zero setting on north. 


16.7 

203.4 

800 

1 

240 

222 

8.0 


25.6 

221.7 

960 

460 

242 

8.6 


21.35 

225. 1 

1,736 

680 

233 

11.3 


21.35 

222. 6 

2,272 

890 

205 

9.6 


21.2 

217.2 

2,840 

1,100 

195 

10.0 


21.05 

213.8 

3,380 

1,300 

194 

10.0 


20.7 

210.2 

3,968 

1,500 

196 

9.S 


20. 65 

209.5 

4, 508 

1,700 

206 

6.2 


21.9 

20.8. 5 

4, 728 

1,900 

156 

3.0 


23.95 

205.9 

4,732 

2,100 

114 

7.1 


25. 95 

199.2 

4, 724 

2,300 

108 

10.8 


27.9 

190.3 

4, 720 

2,500 

105 

12.0 


29.2 

183.0 

4,832 

2,700 

80 

14.0 


33.3 

169.5 

4,420 

2,900 

08 

17.8 


35.1 

155.7 

4,408 

3, 100 

72 

16.2 


35.6 

144.7 

4,612 

3,300 

73 

12.8 


35.85 

137.3 

4,840 

3,500 

67 

13.2 


35.5 

127.4 

5, 180 

3,700 

67 

15.2 


34.3 

120.0 

5,720 

3,900 

66 

16.8 


32.65 

111.3 

6,400 

4,100 

xo 

19.6 


29.2 

108.6 

7,680 

4, 300 

81 

19.3 


27. 95 

103.3 

8,480 

4,500 

63 

18.4 


1.3 

345.6 

Chec 

.ked. 




Theodolite number, 17396 

Observer, Patrick Henry 

Recorder, John Doe 

Disappearance due to haze 


I 

1 Minute. 

1 ! 

!| 

Elevation 

angle. 

Azimuth 

angle. 

Distance 
from 
observar 
tion point. 

m. 

Altitude. 

m. 

Wind 

direction. 

Wind 

velocity. 

m. p. 5 . 

1 0 



Zero settin 
























































































































































































Theodolite number, . . 

Observer, 

Recorder, 

Disappearance due to . 


Diameter at full lift — 

Vertical, 80.0; hor. 74.0 cm. 

Weight, 38 gm. 

Free lift, 193 gm. 

Total lift, 231 gm. 

Rate of ascent from— 

Tables, 20')m. p.m. 

T-A curve, m. p. m. 

Type of balloon, 6" Red. 


Clouds. 

Amt. 

Ivind. 

Dir. 

Upper 

Inter 

1 

Ci 

wsw. 

Lower 

1 

Cu 

NNE. 


Surface wind direction, NNE. 

velocity, lOm/h. 4.5 m/s. 

Temperature, 23°..3-lS“.5 C. 

Pressure, 1,017.9-1,021.7 mb. 

Humidity, 62%. 


Baseline, ; length, 

Azimuth, 

Visibility, Good. 

Sun, ...‘ Bright. 

Notes, 

No ascension for — 

a. m. Date p. m. 

low clouds. 9. rain. 


Now that all is in readiness for the observation, the 
ascension will be started, or the balloon will be released. 
The recorder will be provided with Forms No. 1110-Aer. 
on a clip board, hard pencil, slide rule, and watch, d’ho 
observer will hold the inflated balloon near to and about 
level with the theodolite head, until the signal of "read” 
(or relea°e) is pronounced by recorder or is given by the 
time-interval clock. If the time-interval clock is used the 
balloon will be held in readiness at the first buz/., and 
released on the second buzz. The exact time of release 
to the nearest minfito is noted and recorded in the proper 
space at the top of Form No. 1110-Aer. If the watch 
alone is depended uj)on for time, then the recorder will 
be forced to watch the time and call out the signals 
"warning” and "read” as they occur. By the latter 
system of ti.mc marking the balloosi will bo placed in 
readiness at the signal "warning” from the recorder at 
the lifty-fifth second, and released at the following signal 
of "read,” at the sixtieth second. Also the exact time 
of release is noted and entered upon Form No. 11 lO-Acr. 


Suppose the starting time to be 8:26 a. m. As the bal- 
loon rises and moves out from the station (he observer 
will determine the direction of Avind movement, to the 
nearest of the 16 compass points, which he will call to 
the recorder, who will enter the same on Form No. 1110- 
Acr. Suppose this to be NNE. Note that the wind 
direction Avill be just opposite to that toward which the 
balloon moves. 

As soon as the balloon has moved aAvay from the obser- 
vation point sufficiently, the observer will sight the main 
tube of the telescope upon the balloon, by moans of ball 
and V sight, then tlnnwing in both tangent scroAVS I T 
and HT, figure 35, continue to sight balloon over the 
main tulie while turning the tangent screws to keep the 
theodolite trained upon the balloon. Note that object 
end of telescope is always inclined toward the left as 
the observer looks through the front; that is, the ('Un'a- 
tion angle at VV, figure 35, must never he greater than 
90 degrees. When the rate and character of motion to 
keep the balloon in lino of sight have been attained, con- 


INSTIUJCTIONS FOR AFROLOCHCAL OHSFRVFRS. 


tinuo tlie tnovcMucnt, and quickly change the position of 
the eye to look through the telescope at front or eyepiece. 
If the rate of movement has boon properly judged, the 
balloon will appear in the licld near the intersection of 
the cross hairs. Thereafter the observer will keep the 
balloon in the held by suitable movement of the tangent 
screws. 

When the surface wind velocity is low, oftentimes 
there will be much difliculty experienced in placing the 
balloon in the field of the theodolite. Under siich con- 
ditions much assistance can be given by the recorder. 
The observer posts himself at the front of the telescope 
with hands placed on the respective disengaged tangent 
screws. The recorder, with one hand on the telescope 
standard and the other on the main tube of the telescope, 
will turn the telescope until the vertical plane of move- 
ment is in line with the btxlloon, and, holding in this 
position, will slowly turn the telescope over its vertical 
axis until the balloon comes into the field of the tele- 
scope. When this occurs, the observer will throw in the 
tangent screws and proceed as directed above. 

Fifty-five seconds after the release of the balloon, a 
signal of "warning” vdll be given, either by the recorder 
or by the time interval clock. When this signal is given, 
the observer ’will bring the intersection of the cross hairs 
directly over the balloon and keep it there until the 
second signal of “read” is given, when the motion will 
be stopped to allow the reading of the angles. The 
recorder, at the “warning” signal, will post himself just 
l)eliind the observer and a little to the right, so that he 
can easily see both elevation and azimuth verniers, and 
make a mental note of the degrees of each. Then at the 
signal “read,” as quickly as possible after the motion of 
tangent screws has been stopped, the angles of elevation 
and azimuth will be read and recorded on Form No. 
niO-Aer. Always read the azimuth angle from the 
same horizontal vernier by which the theodolite has been 
oi’iented. 

Ordinarily the observer will read one angle and the 
recorder will read the other. Whether the observer reads 
the elevation angle or the azimuth angle depends largely 
upon the way the base plate is oriented. If the orienta- 
tion setting is on the right horizontal vernier IIV, figure 
3 . 0 , it is better for the observer to read the azimuth angle 
and the recorder the elevation angle, but if the orienta- 
tion setting is on the 4.5° horizontal vernier hv, figure 
35, then it is better for the observer to read the elevation 
angle and the recorder the azimuth angle. In any event, 
the observer should not attempt to read eilher angle dur- 
ing the first five minutes or more, foi' during this time 
the lateral movement, of the balloon is so groat in com- 
parison with the field of the telescope that if is easily lost 
from the field, and this often results in the entire loss of 
time and material. The data for a minute or so might 
better be lost than to lose the balloon at this early stage. 
The recorder has nothing else to do af that time but 
read the angles. 


73 

To read either of the angles it is not necessary for the 
observqr to remove his eye from th(5 telescope tube, and 
thereby lose the focus of balloon, but he may read cither 
angle with the other eye. To read, retain the eye in the 
position as though peering tluough telescope and cast the 
other eye upon the vernier to be read. A little practice 
will prove this to be as simple and easy as though reading 
with both eyes. 

The observer will find that much relief is obtained, and 
much eye strain eliminated, by observing with both eyes 
open. Do not squint, or close the unused eye. A little 
practice will enable the observer to keep one eye at the 
instrument and read one angle with the other eye without 
difficulty. Wlien he becomes proficient, even though the 
gaze of the one eye may be directed upon one or the other 
of the verniers, the other eye will gain and register an 
impression of the movement of the balloon, and should 
the balloon pass a little from the field during the reading, 
it may be regained readily by aid of the movement just 
mentally registered. 

Many instances will arise, however, wherein the ob- 
server will be unable to read either angle due to the fact 
that the balloon movement is so rapid as to require his 
full attention. In such cases, the recorder will read both 
angles, reading that first wliich the observer indicates is 
changing the more rapidly. A reading should be missed 
rather than be the means of losing the balloon. During 
the first 2 to 4 minutes the balloon can generally be seen 
by the naked eye, and thus easily placed in the field again. 
In a few instances, principally when the balloon turns and 
comes back directly over the station, the balloon move- 
ment will be more rapid than can be followed by turning 
of the tangent screws. However, loss of the balloon can 
be prevented without much dilTiculty if the following 
instructions are closely followed. While grasping the 
horizontal tangent screws, TIT, figure 35, between the 
thumb and forefinger of the right hand, extend the 
middle finger past the 45° horizontal vernier, hv, figure 
35, to rest upon the threaded groove of the baseplate, 
HP, figure 35, just below the edge of the revolving plate 
of the telescope standard. Letting this act as a brake, 
carefully throw out the tangent screw and retain the 
finger so placed. It is unnecessary to release the hand- 
hold upon the knurled head of the tangent screw. It acts 
as a rest for the hand. In a similar maniuu- the middle 
fiTiger of the left hand is extended until the ball of the 
finger is plac(al over the small space between the back 
edge of the vertical circle, VC, figure 35, and the pivot 
bearing near the middle of vortical tangent screw. 
Exercise a linn j)ressuro here, then throw out vertical 
tangent screw and shift the thumb and forefinger to grip 
the edge of vertical circle, VC, figure 35. Idie middle 
finger in each case acts as a brake, steadying the move- 
ment of the telescope through the respective planes. 
With the fingers so placed and a little careful judgniont 
on the part of the observer, it is an easy matter to follow 
a balloon going overhead at a good rate of speed. When 


74 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


the rate of movement has diminished sufficiently, the 
tangent screws are gradually thrown in again and the 
ordinary procedure followed. 

In single-theodolite observations the angles will be read 
to the nearest tenth of a degree (see description of vernier 
and figs. 36 and 37), and only at the completion of the 
minute as signaled by the time interval clock or the 
recorder. At the signal “warning” it is well to read the 
angles to the point of ascertaining the whole degrees, 
then the final reading or the reading to tenths of degrees 
can be made in much less time and directly at the “read” 
signal. It is practically necessary that the angles be 
read quickly and accurately. Comparatively small errors 
in reading angles can be detected whenr the run is carefully 
plotted. Thus the necessity for quick and accurate 
work. 

As soon as the angles are read, the observer will bring 
the balloon near the center of the field by means of the 
tangent screws, where he will keep it until the following 
“warning” signal is given. In the meantime the 
recorder will enter the reading that he has made in the 
proper column on Form No. lllO-Aer., and opposite the 
corresponding minute. Suppose the azimuth angle for 
the first minute, read by the recorder from the 45° 
horizontal azimuth vernier, is 203°. 4; this he will record 
in the column under azimuth angle and opposite 1 in the 
minute column. The observer then calls out the angle 
which he has read and the recorder enters this; e. g., 
16°. 7 in the column headed “Elevation angle.” 

During the time that is left between the readings the 
recorder will compute the values for the column headed 
“Distance from observation point” with the slide rule. 
Explanation of this process will be taken up in following 
sections. doing the computation at this time fully 
25 per cent of the working time of an observation will 
be saved, and permit an earlier filing of the coded mes- 
sage in the telegraph office. At the recurrence of the 
“warning” signal all other duties will be suspended 
and the full attention of both men given to the placing 
of balloon on cross hairs and the accurate determination 
of the angles. This same procedure obtains so long 
as the balloon can be kept in sight. When the balloon 
disappears, the observer will call out the reason for such 
disappearance and then check the setting and orientation 
of the theodolite. This reason of disappearance and the 
residts of rechecking will be entered on Form No. 1110- 
Aer. in the proper spaces. Let I’able 19 be the Form 
No. lllO-Aer. of an observation containing the above 
mentioned data. 

When the orientation setting is checked there is seldom 
any change necessary to be made. When the change 
amounts to a few tenths of a degree there is little that 
can he done in the way of correction, unless it is evident 
that the setting has been in error throughout the flight. 
Corrections should be made to the azimuth angles when 
there is reason to believe that such corrections should be 
made. This will emphasize the need of care and atten- 


tion to the minutest detail throughout the whole of the 
observational work. 

The cause of disappearance will he recorded according 
to the following reasons. They stand in their order of 
frequency and relative importance. 

1. Clouds: 

Against. 

In base of. 

Obsonred by. 

2. Burst. 

3. Distance. 

4. Haze. 

5. Sun. 

6. Obscured by — 

Tower. 

Chimney. 

Etc. 

7. Overhead: 

High elevation angle. 

Rapid change of angles. 

8. Accident: 

Kicking of theodolite. 

Allowed to pass off field. 

Yilwation of theodolite, etc. 

9. Abandoned. 

When the disappearance is due to clouds, it will he 
specifically stated whether against, in, or behind clouds. 
If this is not known, a statement to that effect should 
be made. If the balloon is seen to enter the base of 
clouds, particular attention will be given to the azimuth 
and elevation angles of the balloon, and the fractional 
part of the minute of the balloon’s disappearance after 
the last minute reailing. The* product of this fraction 
of a minute into the rate of ascent, when added to the 
altitude of balloon for the last minute observed, will give 
the altitude of the cloud base. The direction and velocity 
of clouds is then computed in the same manner as for any 
other specific point of the projection. (See section 5.) 

Disappearance due to distance will not occur during a 
short flight, except in rare cases where there is a very 
strong wind at the surface and aloft. A distance of 10 
kilometers is the minimum value for this entry. Hori- 
zontal distances of less than that amount are due to 
other causes, possibly haze, fog, etc. Occasionally the 
balloon will run across the sun’s disk, making observation 
impossible; however, such instances should bo rare, since 
the theodolites now in use have a special eyepiece with 
pivoted disc of colored glass, permitting observation 
until the balloon actually begins to cross the sun. 
Other instances will occur when the balloon will be 
lost behind the anemometer tower, chimney, or other 
obstruction. At a properly selected station possessing 
low angle of obstructions this reason will bo of small 
frequency. The entry will be made, “obscured by 
” During periods of low surface wind veloc- 
ity, the elevation angles for the first few minutes will be 
relatively high. In fact, the balloon may be directly 
overhead. The balloon may change its course and come 
back directly over the observation station. The change 
of the angles, osj)ocially the azimuth angle, will then be 


INSTUUCTTONS FOR AKROLOGlCAr. OBSERVFRS. 


rapid. In case of disappenranco duo to oithor of tlioso 
Cfliisps an explanatory noto should bo ontorod after the on- 
trj’^ " Ovorhoad.” Thoro will be a certain amount of loss 
due to accident, which is caused by the kicking or knocking 
of theodolite sufhciently to throw the balloon out of the 
field. This disappearance is due to carelessness, and 
with due attention to the work at hand will be eliminated 
altogether. vStrong surface winds will sometimes throw 
the theodolite into such a state of vibration that the 
balloon can not be accurately^ placed at the cross hairs, 
and this will finally result in the loss of balloon altogether. 
An explanatory note must also accompany the entry of 
accident. There are but few cases when the balloon will 
be abandoned, principally to permit the early file of a 
coded message containing the observed data. 

The checking of the setting and orientation is accom- 
plished by setting the telescope of the theodolite upon 
the orientation point and noting the readings at the same 
verniers by which the theodolite was originally oriented. 
If there is no change within a few' tenths of a degree, 
the readings will be entered in the proper columns on the 
second line under the last entry of observed angles, as 
"check.” Otherwise, corrections will be made on the 
observed data. In this instance the setting at the end 
of the observation was identical v/ith that of the initial 
orientation, 1°.3 elevation, and 345°. 6, azimuth angle. 

Douhle-theodolite observations require the cooperation 
of three, four, and sometimes more men, all depending 
upon the arrangement of station and scope of w'ork at 
hand. The prevailing arrangement of double theodolite 
station requires four men for the observation work, an 
observer and a recorder posted at each station. Their 
respective duties are nearly identical with those in a 
single-theodolite observation. 

Little or no slide-rule computation work is done while 
the observation is in progress. During the time that the 
primary station is preparing the balloon and setting the 
theodolite, those detailed for duty at the secondary 
station will have arrived at that station, set, and oriented 
their theodolite according to one of the methods set 
forth in "Orientation of theodolite,” section 2. 

Each station will bo provided with a signal flag about 
3 feet square, and attached to a short pole, or staff, to 
facilitate signaling to the other station. When all is 
ready at cither station the signal flag will bo cxpo.sed so 
that the men at the other station can see it. When 
both preparation signals arc posted, all is in readiness 
for the a.scent. The actual mode of signaling of the 
balloon release should be adopted and understood by all 
of the observers. Two methods ai’e here given, both of 
which have been found to be very satisfactory. In the 
first, when the preparation signal at the primary station 
is answered by that of the secondary station, the recorder 
at the primary station, commencing one minute before 
the balloon is to be released, will wave the flag vigor- 
ously and in plain view of the observer at the secondary 
station for a period of 55 seconds. At the end of this 


time the flag is poiser! high above the liead for the 
siicceeding interval of five seconds, at the expiration of 
which the flag is brought down with a decided stroke. 
At the final downward stroke, the observer, who has 
been holding the balloon near the head of the instru- 
ment, wdll release it. The time of release will be noted 
and recorded at both stations, their time pieces having 
been co.mpared before the flight. When the time pieces 
are not compared and set together previous to the 
flight, there is likely to be much inconvenience at the 
secondary station in regard to the w^atch time of w^arn- 
ing and read signals. They may come at 21, 29, 51, or 
any other odd second. 

Another method of signaling the release of the balloon 
is to expose the inflated balloon at arms’ length above 
the head in full view' of the observer at the secondary 
station. 'VMien all is in readiness for the release, the 
observer at the primary station w'ill low'er the balloon 
to the ground about 10 seconds before the time of release, 
w'here he will hold it for five seconds, at which time he 
W'ill raise it to the initial position above the head. On 
the expiration of the minute, or on the sixtieth second, 
he W'ill release the balloon. The recorder at each station 
W'ill note and record the time of release as in the pre- 
ceding method. 

As soon as the balloon is released, the signal Hags w'ill 
be taken down at both stations by the recorder. The 
observers at both stations w'ill immediately sight their 
theodolite upon the balloon and follow closely as in- 
structed under single-theodolite observation. The ob- 
server at the secondary station w'ill have little (iiniculty 
in this matter, since his theodolite is already trained 
upon the balloon at the primar}' station. When the 
balloon is released he has only to follow' it by manipu- 
lation of the tangent screw’s. Location of the b.alloon 
at the primary station will be identical w'ith that during 
a single-theodolite observation. 

At each station the recorder w'ill have to note the time 
and call signals for the readings which will be taken at the 
end of each successive minute from the time the b.alloon 
is released. The data at primaiy station w’ill be entered 
on left-hand half of Form No. lllO-Aer., Table 20, and 
when that half of the sheet is filled up, a second sheet 
W'ill be used. In single-theodolite work the second or 
right-hand half of the sheet would be useil for the con- 
tinuation of the data, but with the double-theodolite 
work the second half of the sheet is reserved for the entry 
of the data of the other station. 'I'hus w'e have all the 
observed data for any one minute at both stations, on 
the same sheet and in the same lines. The ilata at the 
secondary station w’ill be entered on the right-hand side 
of the sheet only. Foi in No. 1 1 lO -Aer. will provddi' for a 
single-theodolite run of GO ndnutes, but onl_y for a run of 
30 minutes for double-theodolite work. Table 20. At the 
completion of the observation the data from the one 
station W’ill be copied on the Form No. 1110 Aer. of the 
other. 


7G 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


[Form No. lU0-.\or.] 


Station (place of observation). 
Ascension number, 1111. 


Table 20 . 

U. ^■. DEPARTMENT OF AGRICULTURE, WEATHER BUREAU. 

Pilot Balloon Ascension Report. 

Date, .July 14, 1920. 

Number of theodolites used, 2. 


Starting time,? :2o a. 
90th meridian time,. . . 


Observation point, A of A B. Altitude, 228.14 m. 


Minute. 

Elevation 

angle. 

Azimuth 

angle. 

Distance 
from 
observa- 
tion point. 
m. 

Altitude. 

m. 

Wind 

direction. 

Wuid 

velocity. 

m. p. 8. 

n 

0.0 

0.0 

Zero setting on north. 

1 

31.1 

43.5 

400 

242 

56 

6.9 

2 

28.2 

56.5 

840 

450 

82 

8.4 


26.4 

72.0 

1,320 

656 

93 

11.9 

4 

21.4 

79.3 

2,160 

850 

89 

13.7 

0 

19.6 

81.6 

2,930 

1,044 

89 

11.7 

r> 

19.2 

83. 1 

3, 555 

1, 240 

89 

10.4 

7 

19.0 

83.8 

-1, 160 

1,435 

94 

11.7 

8 

18.2 

86.2 

4,975 

1,635 

101 

12.9 

9 

17.6 

88.3 

5,650 

1, 795 

97 

13.3 

10 

16.9 

88.9 

6,510 

2,005 

90 

16.1 

11 

16.3 

88.7 

7, 600 

2,225 

87 

18.0 























Observation point, B of A B. Altitude, 230.33 m. 


Minute. 

Elevation 

angle. 

Azimuth 

angle. 

! Distance 
j from 
j observa- 
tion point. 
TO. 

Altitude. 

m. 

Wind 

direction. 

Wind 

velocity. 

TO. p. s. 

0 

0.0 

0.0 

! Zero setting on north. 

1 

7.1 

314.3 





2 


330.4 





3 

25.3 

349.4 





4 

29.7 

24.9 





5 

28.0 

45.1 





6 

20.8 






7 

25.1 

62.0 





8 

24.2 

69.5 





9 

22.8 

74.9 





10 

21.2 

77.9 





11 

19.8 

79.4 





12 

18.9 

81.2 





13 

18.3 

83.6 





14 

18.0 

8.5.2 







Check. 






TheodoUte number, . 

Observer, 

Recorder, 

Disappearance due to; 


13394. 

John Doe. 1 

Patrick Henry, j 

Obscured by St. Cu. cloud. 1 


Theodolite number, . . 

Observer 

Recorder, 

Disappearance due to; 


12348. 

James D. Jones. 

M. S. Smith. 

Enter St. Cu. cloud. 


Diameter at full lift — 

Vertical, 75..5; hor., 71.0 cm. 

Weight, 

Free lift, 

Total Uft, 

Rate of ascent from — 

Tables, 

T-A. curve, 

Type of balloon, 


..37. 5 gm. 
.172. Ogm. 
.209. 5 gm. 


,191 m. p. m. 
.202 m. p. m. 
C.-R.-6" 


Clouds. 

•Amt. 

ICind. 

Dir. 

Upper 




Inter 

2 

A. St 

W. 

Lower 

8 

St. Cu. 

W. 


Surface wind, direction, SW. 

velocity, 4.5 ni/s. 

Temperature, 22°. 5 C. 

Pres.sure, 989. 2 mb. 

Humidity, 89%. 


Base line, 

Azimuth, 

Visibility 

Sun, 

Notes 


A. B.; length, 1781.86. 

122°.5o. 

Fair. 

Obscured. 

Weather cloudy. 


The balloon will bo followed as long as it can be kept 
in sight. Never should it be abandoned at either station 
before disappearance, without strong reasons for doing 
so. However, as soon as the balloon is lost at either 
station the flag will be raised as a signal to the other 
station. In cases where the balloon is lost sight of at one 
station for an appreciably longer period than at the 
other, the remainder of the flight beyond the time of 
disappearance at the one station may be computed by 
the single-theodolite method. 

Following the disappearance of the balloon, and before 
the theodolite is disturbed from its setting, a check of the 
levels and orientatiojj will be made. Note that the azi- 
muth bearing is read from the same vernier by which the 
theodolite was oriented. If there are no coiToctions to 
be made the “check” will follow in the second line after 
the last line of observed data. The data will then be 
plotted and reduced in the same way as in the making of a 
single-theodolite observation. The methods of plotting 
vaiy to some extent, however, and will be taken up in 
regular order in subsequent paragraphs. 

In but few cases will slide-rule computations be per- 
formed during the double-theodolite observation. In 
many cases, however, it may be possible to do the com- 
putation and plotting while the flight is in progress. In 
such instances the computing work is generally carried 


on at a third point, which has telephonic communication 
with both observation stations. All three terminals of 
the line end in a head set, which allows free use of hands, 
and yet provides for the immediate use of the telephone. 
A time-interval system is easily installed in the telephone 
line, and will serve to mark the release of the balloon and 
the observation signals for each of the successive min- 
utes, making it possible to read the angles at both stations 
at the same instant. Communication from the primary 
station will prepare the secondary station for the time 
of balloon release. 

When the observing stations are connected by tele- 
phone, then an observation can be canled on with only 
three men. But if computation and plotting are carried 
on during the flight, then four or more men will be needed. 
The regular force of two men obtains at the primary sta- 
tion, where they perform their regular dulies much the 
same as in a single-theodolite observation, with the ex- 
ception that the recorder, speaking plainly, calls the ob- 
served data to the third j)arty in the computing room. 
At the secondary station one man can easily observe the 
balloon and read the azimuth angle, which he calls to 
the computer over the telephone. Where this practice 
is carried on it is best to orient the theodolite by the right 
azimuth vernier. The computer, or the parly in the 
computing room, receives and records all data from both 


INSTRUCTIONS FOR AFROLOCICAL OBSFRVFRS. 


77 


.stations, |)laoing that of primary station on the left-hand 
half of sheet and that of the secondary station on the 
right-hand half of the sheet. He tlum immediately plots 
the data, or constructs the horizontal projection, before 
the lapse of tlui wliole minute. The recorder at the pri- 
mary station A\ill receive and record the angle or angles 
reporteil by the secondary sltilion. This will be the 
original recoj'd and should be rendered in carbon with 
data from both stations and on tlie same sheet or sheets. 

At any convenient time during the ascension the visi- 
bility and condition of the sun will be noted and recorded 
according to the following scales: 


Visibility scale. Limiting 

distance 

.Scale. Descriptive term. (meters). 

0 Dense fog — prominent objects not visible at 50 

1 Very bad — prominent objects not vdsible at 200 

2 Bad — prominent objects not visible at 500 

3 Very poor — prominent objects not visible at 1, 000 

4 Poor — prominent objects not vdsible at 2, 000 

5 Indifferent — prominent objects not visible at 4, 000 

0 Fair — prominent objects not visible at 7,000 

7 Good — prominent objects not visible at 12, 000 

S Ver\’ good — prominent objects not visible at 30,000 

9 Excellent — prominent objects visible beyond 30, OOit 


This scale is nearly self-explanatory. The distances 
can be laid off on a map of the section of the country, and 
prominent objects selected us the points of reference. 

Sun brightness scale. 

1. Brilliant — Of rare occurrence; atmosjrhere must be exceptionally 

clear; smooth surfaces and shiny objects glisten. 

2. Bright — As in a normal clear sky. 

3. Intermittent — Alternate sun and shadow; sky containing clouds of 

the bunch formation. 

4. Through clouds — Sun quite dimmed by continuous clouds; grayish 

appearance. 

5. Faint — Disk of sun barely visible through clouds of ."heel formation, 

as Gi. St., A. St., or St. 

(). Obscured — Sun completely hidden by any dense cloud layer. 

This scale is also self-explanatory. In each case the sun 
brightno.ss and the visibility M’ill be entt'red on the Form, 
using for this purpose the apjrropriate terms rather than 
the numbers; e. g., “brilliant,” “faint,” “dense fog,” etc. 

Omission of an Ascension . — It sometimes happens 
that at the time of the scheduled pilot-balloon observa- 
tion the weather conditions are such that an observer 
might carelessly or indifFcuently call off an ascension 
when it is really possible to make a satisfactory observa- 
tion. For example, a light sprinkle of rain might be 
sufficient to give the observer the excuse for calling off the 
ascension, even when the drops are so few as to causi^ 
neither injury to the theodolite, discomfort to the ob- 
server, the early disappearance of the balloon, nor appre- 
ciable retardation in the ascensional rate of the balloon. 
Snow Hurries of short duration often preclude an ascen- 
sion at the scheduled time, when a very few minutes 
later an ascension would be easily possible and worth 
while. It is expected that an ascension will be made 
within 30 minutes of the scheduled time, either before 
or after, if weather conditions are such as not positively 


to forbid the making of an ascension. It is recognized 
that there are times when it would be a waste of balloon 
and gas to attempt an ascension; but, on the other hand, 
conditions must not be too easily and cpiickly dismissed 
as belonging to this class, in general, it may l)e said 
that an ascension should be made under all conditions 
except those which incur danger to the instrument, 
marked discomfort and possible injury to the health of 
the observers, or a loss of the balloon below 2.50 meters. 
If such conditions disappear within 30 mmutes of the 
time of the scheduled observation the ascension should 
be made; and if it is judged that such conditions may 
occur at the time of observation, the ascension should be 
begun early, possibly as much as a half hour. 

It is recognized that, in the last analysis, the question 
of omitting an ascension is one that must be decided 
locally, and that no ironclad rules can be set down in 
instructions. But it is a question that has a strong 
personal element, and is one that must be answered 
conscientiously by those concerned. Times when ascen- 
sions are likely to be omitted owing to unfavorable 
weather conditions are often those which would be of 
Greatest scientific value. The observer should bear in 

o 

mind at all times the value of the data he is securing 
and the many uses to which they may be put, and he 
should try to cultivate such a spirit of sincerity. This, 
coupled with good judgment, is certain to result in the 
satisfactory collection of aerological data. 

5. COMPUTATION. 

The second part in making an observation, or the 
computation, may be accomplished by either one of 
three methods; that is, by slide-rule method, graphical 
method, or by logarithmic computation. The computa- 
tion of single-theodolite observations is nearly always 
done by means of the slide-rule method, though the 
gi-aphical method is frequently used when men doing 
observation work are not proficient in manipulation of 
the slide rule. The slide-rule method saves much time 
when there is a limited period during whicli the observa- 
tion must be completed, and for the same amount of 
time expended on either method will give results more 
closely comparable with the results liy logarithms. 
The logarithmic method is seldom used in single-theodolite 
computation because of the time involved in the work. 
Bructically the only use made of it is as a means of check- 
ing the computation l)y either of the otlior methods. 

The slide-rule method provides a means whereby the 
observed data can lie reduced during the observation 
itself for the construction of the horizontal projection 
immediately after the completion of the ascension, 
whereas by either of the other two methods tlie computa- 
tion must be suspended until the making of the obser- 
vation is compli te, and l)y one oi these until alter the 
hoi’izontal projc'ction is made. By the graphical method 
more than the observed data is not determined until 
after the horizontal projection has been made. 


78 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


Double-theodolite computation is generally accom- 
plished either by the graphical method or by the loga- 
rithmic method. The slide rule is frequently used for the 
solving of the trigonometric formula3 when immediate 
general results are desired. The greatest accuracy is 
attained by the logarithmic method, though it involves 
considerably more time than the graphical method. 
Computation by logarithmic method is preferred, though 
the graphical method will be used frequently. All 
methods will be given full discussion in the following 
paragraphs. 

Method I. (1). Single-theodolite compviation, slide-rule 
method. — The slide rule used by the Weather Bureau for _ 
the computation of pilot-balloon observations is the 
K. & E. pol 3 'phase duplex slide rule. It is a 10-inch rule 
of mahogany, with the scales graduated upon a white 
celluloid base. The principle of the slide rule is purely 
logarithmic, and each scale is graduated after that prin- 
ciple, but the manipulation of it and the work done 
with it are purely mechanical and can be readily taken 
up without the slightest knowledge of logarithms. 

The scales of the slide rule in general use for pilot- 
balloon computation are the tangent scale T, the sine 
scale S, and the associate scales of D and A. For single- 
theodolite computation, little but the T and the D scales 
will be used, and these in conjunction with the formula 

tan e =^, will be sufficient. 

e = the observed elevation angle for any one minute, 
which is found on T scale of central slide of rule. 

7i. = the theoretical altitude or elevation of balloon at 
end of each minute. It is the product of ascen- 
sional rate into time in minutes from release of 
balloon. This value is found on the lower or D 
scale of the slide rule. 

d = the horizontal distance from the observation point 
to a point directly underneath the balloon. 

A complete manual of instructions is furnished with 
each slide rule, and for that reason but little attention 
need be given here to the manipulation of the slide rule. 
Therefore, special reference is made to sections 3 and 7, 
and to pages 2 and 16 of the “Mannheim and Pol^-phase 
Slide Rule Manual.” The supplement at the end of the 
manual will give much information of practical interest. 

Slide-rule computation for pilot-balloon work is af- 
fected to some extent by the elevation angle, which 
separates the work into two phases, namely, elevation 
angles less than 45° and elevation angles greater than 
45°. Wliile an explanation of computation involving an 
elevation angle of more than 45° is given early in section 
7 of the manual, the direct application to pilot-balloon 
computation can be stated in simpler form, and will 
follow later. In ordinary computation, the elevation 
angle is less than 45°, and in such cases the j)rocedure is 
simple enough. 

To compute the value d from the formula, tan ^ = 
where e is less than 45°, the runner of the slide rule is 


set at h, in meters, on the D scale of slide rule, and then 
central slide is moved until the elevation angle e (for the 
same minute) on scale T is brought under the hair fine 
of runner. The value of d is then read from the D scale 
of slide rule under the index of the central slide. In 
some instances this will be the right index and at other 
times it will be the left index. With reference to data 
sheet for single-theodolite observation. Table 19, to com- 
pute the distance out for the first minute, set the runner 
of slide rule on 240 of the D scale, then adjust the central 
slide until 16°. 7 (the elevation angle for the same minute) 
on the tangent scale is placed under the hair line of 
runner and coincident with 240 on the D scale. Under 
the right index of slide and on the D scale read 800 meters. 
Notice that the subdivisions on the T scale for angles less 
than 20° are equivalent to 5 minutes of arc and those 
subdivisions from 20° to 45° are equivalent to 10 min- 
utes of arc, while the divisions of angles as read from the 
theodolite are in degrees and tenths of degrees. There- 
fore, it will be necessary to convert the tenths of degrees 
to minutes in order to make the settings of T scale ac- 
curate. This is a simple mental operation accomplished 
by multipl^dng the tenths of the angle by 6, the resulting 
product being the fractional part of the angle converted 
to minutes. This value found will be recorded on the 
Form No. 1110-Aer., in the column headed “Distance 
from observation point.” Proceed with the remainder 
of the flight in the same way, making sure that each 
computation is made onl}' on altitude and corresponding 
elevation angle. 

W^'hen the elevation angle is above 45°, set the index 
of the T scale over h found on D scale, set the hair line 
of the runner over the elevation angle found on T scale, 
and read the value d under the hair line of rmmer on 
D scale. This value is the (quantity sought, and is to be 
recorded in the corresponding space on Form No. 1 1 10-Aer. 
As an examj)le, suppose the elevation angle is 54°. 9 and 
the altitude of the balloon is 600 meters. To compute 
the value of d for this case wo would set the index of 
central slide over 600 on the D scale, then on the T scale 
of the central slide we would find the angle 54°. 9 and 
place the hair line of the runner thereon. Under Iho 
hair line and on the D scale we would read off the value 
of d, or 422 meters. It will bo noticed that the T scale 
provided only for angles of 45° or less, and since the func- 
tion of an angle is ecpial to the cofunction of the comple- 
mentary angle, the operation involves a reversal of the 
method when an angle of more than 45° is recorded. To 
simplify the settings when the angles are greater than 
45°, lot the 5° divisions of the tangent scale be rcvmarked 
beginning at the 40° ilivision which will bo designated 
as 50°; 30° will bo 60°, etc. If these divisions are marked 
upon the celluloid surface of the rule in red ink, it will 
bo found to assist greatly in the settings for angles greater 
than 45°. Lot it bo noticed and used as a check that the 
results of all slide-rule computations made on angles of 
elevation less than 45° will be greater than the h value on 
which the computation was made. Similarly, the results 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


79 


of all sliiie-rulo computations made on an{ 2 ;los of elevation 
greater than 45° will bo Zfssjthat the corresponding h factor. 

Some difTiculty is had in making the final close adjust- 
ments of the central slide during the computation. The 
following method, when closely followed, will eliminate 
any such trouble; Hold the rule between the thumb 
and firet finger with one hand at either end of the slide 
rule so that the ball of the thumb and the tip of the first 
finger are placed over the seam of the slide rule between 
the rule itself and the central slide. Now, to make the 
setting, apply the principle of the parallel rule; that is, 
while firmly holding the rule as directed, extend one hand 
and arm while the other is drawn backward. This 
motion will cause the slide in the rxile to move gradually 
and smoothly toward the end of rule which is being 
extended. Reversing the operation will drive it to the 
other end. By performing this movement slowly, the 
setting can be made as close as the eye is able to deter- 
mine. 

Plotting, or the construction of the horizontal projection . — • 
Immediately after the observation is taken and com- 
putation is completed, the data vdll be plotted and re- 
duced. The process of plotting is slightly different for 
the two methods, slide-rule computation and graphical 
method. As a matter of fact, the computation in the 
graphical method is preceded by the plotting or the con- 
struction of the horizontal projection. Plotting from 
logarithmic computation is identical with plotting from 
slide-rule computation, though more accurate, and also a 
much longer operation. 

The plotting board in use throughout the service is 
the most practical apparatus of its kind which has yet 
come to our knowledge. After prolonged study of vari- 
ous methods this board was selected for its simplicity 
and accuracy. It consists of a drafting board about 42 
inches square. Over the central area is glued a circular 
sheet of millimeter cross-section paper. At the center of 
the area, and set into the board, is a brass bearing and 
pin A, figure 45. From the center of this pin or post 
three distance scales are drawn: Scale AC is a single 
scale and so constructed that 1 cm. = 100 m.; Al) is a 
double scale in black and red. The divisions on the 
black scale, or the right side of the scale base, are sucli 
that 1 cm. = 200 m., and the red scale, or that on tlu* 
left side of the scale base, is equal to 1 cm.=--400 ni. 
Let these scales be designated as 1, 2, and 4. The num- 
ber of th<i scale will correspond to tlie nunil)er of hundred 
meters which 1 centimeter will e({ual. Let tin* lines on 
which the scales are graduated be known as tli(‘ indices 
of the d scales, and let the scales tlumiselves be known 
as d-1, d-2, and d-A. At a convenient distance from 
the center, and extending perpendicularly toward the 
right from each of the scale bases, are drawn altitude 
scales EF and GJI. Tlnwe scales are so constructed that 
they are homologous to the respective distance scales; that 
is, 1 cm. = 100 m., 1 cm. = 200 m., and 1 cm. = 400 m. Let 
these scales be known as l-h, 2-4, and 4-4, respectively, 


(o agree with the distance scales so designated. In tlie 
((uadrant to (he right of the, scale base, and near the 
edge of the circular sheet of millimeter paper, is drawn 
a 90-degree arc, gi-aduated in half degna's. This arc is 
to be used for the elevation setting when the f)rojection 
is constructed by (die gi-aphical method. Over the cir- 
cular area of paper and fastened to the brass jiin as a 
center is placed a disk of frosted celluloid with the cir- 
cumference graduated in half degrees. The subdivisions 
of half degrees are made to aid in determining settings of 
azimuth angles when projection is being made. A brass 
arm, AX, plays about the central pin and on the grad- 
uated 90-degree arc for the graphical computation, but 
is not used when the flight is plotted after tlie slide-rule 
computation. Its main use is in graphical jirojections 
of double-theodolite work. 

To plot, or construct, the horizontal projection of the 
computed flight, the plotting board will be arranged with 
the scale selected, 1-d, 2-d, or 4-d, directly in front of 
the operator. The celluloid on plotting board is tlien 
cleared of all previous records by erasing the pencil 
marks with a piece of soft eraser or ar(, gum. Note tha-t 
only soft erasers are used for this purpose. The celluloid 
protractor is then revolved about the center until the 
observed azimuth angle for the minute to be plotted is 
found on the edge of the disk and placed over the index 
of the scale selected. Then taking the computed dis- 
tance out for the same minute as a second factor, a point 
is plotted on the celluloid surface directly over this value 
found on the scale selected. The point is set ofl’, or 
made more prominent, to distinguish it from any other 
point that may have been left upon the board, by en- 
circling, or by marking with a small cross, letting the 
intersection come at the position of the point. The 
method of encircling is recommended. Only veiy soft 
and well-sharpened pencils will be used on the celluloid 
protractor. It is diflicult to place a i)oint accurately 
with a dull point, and a hard, or even a medium soft, 
pencil will not make a mark easily distinguished. 

The average scale selected will be 2-d of the double 
scale AD, figure 45, or that in which 1 cm. = 200 m. 
Scale 1-d, AC, figure 45, will be chosen only when the 
wind movement for the first few minutes is compara- 
tively small, the observation a short one, or the maxi- 
mum distance out less than 5,000 meters. Observations 
of another character than these will be started upon the 
larger of the double scale, 2-d, and if necessary trans- 
ferred to the smallei’ scale 4-(/. As an example see 
horizontal projection for single-theodolite observation 
on figure 45, A, 1, 2, 3 . . . . 21, 22, designated by points 
inclosed with small circles, d'his is the horizontal pro- 
jection for sample flight recorded on Form No. 1110- 
Aer., Table 19. The plot is to the scale 1 cm. - 200 m., 
or scale 2-d. 'Fhe board is arranger! so that this scale 
is directly in front of the operator, then the azimuth 
angle for the first minute 203°. 4, is found on circum- 
ference of the celluloid disk which is revolved until this 


80 


INSTRUCTIONS FOR AKROLOGTCAL OBSERVERS. 


angle is placed over the scale base or index of scale 
used, AD, figure 45. The distance from the observation 
point for the same minute, 800, is then found on the 
scale 2-d and a point placed there directly over the scale 
base, with a soft pencil. Set off by marking with cross or 


encircling with a small circle, and number the point as 1. 
Proceed in the same manner with succeeding minutes 
2, 3, 4, etc. Note that the setting of plotting board in 
this figure is for the third minute of the tabulated data; 
that is, the azimuth angle 225°. 1 is set over the lino 


AD, and point 3 is placed over the scale base on scale 
2-d at a scale distance of 1,736 meters from the observa- 
tion point. The point is inclosed by a circle and marked 
3. Had the flight extended over a greater length of 
time, such that the maximum distance out would have 


exceeded 10, 000 meters, the last two minutes on scale 
2-d would have been plotted on scale l-d whh the same 
azimuth setting. The reason for this will be explained 
later. From the repetition of the two points (he hori- 
zontal j)rojoction will be continued on 4--t/. Had the 



Fig. 4r).— Singlo-thcodolile plotting board. 


INSTRUCTIONS TOR AEROLOGICAL OBSERVERS. 


81 


flight been started on scale \-d, the double plot would 
have taken in the last two points before 5,000 meters 
distance out, or points 10 and 17. That is, point 16 
would have been plotted on both scale 1-cZ, and scale 
2-d, the azimuth setting of 144°. 7 obtaining on both 
scales. Likewise, point 17 would be repeated. 

Method I. {2). Single-theodolite, graphical method. — If 
the grapliical method is substituted for the slide-rule com- 
putation, then the plotting of the horizontal projection 
will be somewhat different, and will in truth precede the 
actual derivation of distance from observation point. 
Slide-rule computation during the observation will not 
be necessary. The only duties of the recorder will be to 
read and record any data pertaining to the observation. 
Directly after completion of the ascension, a horizontal 
projection of observed data will be made on the plotting 
board. By this method, the plotting board will be 
equipped with the brass arm, and arranged with a selected 
distance scale directly in front of the operator, as though 
plotting from slide-rule computation. 

To plot or construct the horizontal projection for any 
minute, find the observed azimuth angle on edge of 
celluloid protractor and set this over the scale base 
selected, then set the beveled edge of the brass arm 
AX, at the observed elevation angle on the 90-degree 
arc in the quadrant of the circle, to the right of the azimuth 
index. Then, with the altitude of the balloon as the 
third factor, find this value on the altitude scale agree- 
ing with the distance scale on which the horizontal pro- 
jection is being made, and follow line through this point 
parallel to the scale base imtil it intersects the edge of 
the brass rule. From this point drop a line perpen- 
dicular to the line just run through the point on the 
elevation scale, to the scale base or index where a point 
will be placed, get off by circle or cross and numbered. 
Horizontal projection A, 1, 2, 3 ... . 21,22, figure 45, 
shows the setting for plotting of the third minute. Scale 
2-d was selected for the plot. The azimuth setting of 
225°. 1, and elevation setting 21°. 4, obtain, as may be 
seen from figure. Now on elevation scale corresponding 
to distance scale, in this case 2-h, the altitude for the 
same minute is found and a line run through this point 
parallel to distance scale index. Careful attention given 
to the millimeter lines of millimeter paper base will aid 
in running the parallels and perpendiculars in the plot- 
ting operation. The altitude for the third minute is 
680 meters. Note that KL, figure 45, runs tlmough 
680 on scale 2-h and parallel to the scale base or index 
of scale 2-d. At the point of intersection, L, between 
this line KL and edge of brass arm, drop a perpendicular 
to the iivdex of scale 2-d, and place the point 3. Note 
that L 3 is perpendicular to index 2-d. The points A, 
L, and 3 determine a right triangle, and with reference 

to formula tan « = , the base A 3 is equivalent to dis- 
tance out, since 3 L is the altitude of balloon and angle 
3 A L, the angular elevation. 


When the observation is plotted by the graphical 
method three unknown values are to be determined from 
the horizontal projection instead of two as in the method 
by slide-rule computation. From the method under 
present discussion, distance from observation point, wind 
direction, and wind velocity must be determined, while 
by the slide-rule method only wind direction and wind 
velocity need be determined from the horizontal projec- 
tion. To determine the distance from observation point 
of points plotted by the graphical method, revolve the 
protractor or celluloid disk until the point in question 
comes directly over the index of distance scale upon which 
horizontal projection is made, then read off the distance 
from the same scale. For example, to find the distance 
out for the third minute in plot A, 1, 2, 3 ... . 21, 22, 
figure 45, bring the third point over the index scale 2-d 
and read the position of point 3 on scale 2-d. By this 
method the distance out seems to be about 1,725 meters 
against 1,736 by the slide-rule method. The general 
average of results obtained by the slide-rule method com- 
pares more closely with results obtained by logarithmic 
computation than do the results from the graphical 
method. Therefore, the slide-rule method should be used 
in preference to the graphical method. Not only is it 
more accurate but it is a much quicker method. 

Method I. {3). Single-theodolite, slide-rule computation, 
graphical cosine plotting. — A third method of graphical 
plotting, convenient, speedy, and very accurate, if 
worked out carefully, is based upon the use of the natural 
cosine value of 0.6000, which reduces, graphically, the 
resulting horizontal distances to velocities in meters per 
second. 

The protractor is prepared for this method of plotting 
by drawing a line, as AT or AV, figure 45, on the milli- 
meter paper in the quadrant to the right of the index of 
each distance-out scale, so that it will make an angle with 
the scale base equal to 53°. 13, or the angle whose natural 
cosine is 0.6000. 

To construct the horizontal projection by this method, 
rotate the celluloid disk until the observed azimuth angle, 
on the edge of the disk, is set over the outer end of AT or 
AV, figure 45. Then, finding the distance from observa- 
tion point on the d scale that has been selected, drop a 
perpendicular from this point and produce until it inter- 
sects the line AT or AV, where a point is placed and set 
off as described in the foregoing methods. Successive 
points for the remainder of the ascension are plotted in 
the same manner. The horizontal projection by this 
method is automatically reduced so that the straight-line 
distance between alternating points is divided by 12, 
which operation converts the horizontal distance trav- 
ersed during a two-minute interval to velocities of wind 
movement in meters per second. 

The observer should have some practice with this 
method and should become thoroughly familiar with i t 
before attempting to make the projection of an actual 
observation. Much care must be taken in running the 


46329—21 6 


82 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 


perpendiculars from the distance scale to the line AT or 
AV, figure 45. It will be noticed that the range of dis- 
tance scale by this method is about 30 per cent less than 
the range of the distance scale of the two preceding 
methods. The particular advantage of this method lies 
in the speed with which the direction and velocity may 
be determined, as will be shown under determination of 
direction in ‘'Reduction of data,” section 6. 

Method /. {4). Single-theodolite, logarithmic computa- 
tion.— This form of computation for single-theodolite 
work involves the use of the same formula as that used 

in slide-rule computation, namely, tan or ^ = 

Any convenient table of logarithms to the fifth place may 
he used. As an example, suppose the balloon to be at an 
altitude h, of 400 meters, and the observed elevation 
angle (e) 34°. 6, then the distance out, d, is found by sub- 
tracting log tan e from log 400 ; 

log 400 =2.60206 

-log tan 34°.6 = 9. 83876 

log d =2.76330 

d =579.83 

and since we use the distance to the nearest whole meter, 
this is reduced to 580 meters, the distance out for that 
reading. 

DouUe-theodolite computation. — While there are nu- 
merous methods of graphical computation for double- 
theodolite observations, the basic principle of all is the 
same. A series of triangles is formed and projected 
upon a horizontal plane where the required parts can be 
conveniently measured by the use of a properly divided 
scale. Some methods are simpler than others and still 
may be retained within the same limits of accuracy. 
Three graphical methods have been carefully studied out 
and favorably accepted for their accuracy, simplicity, and 
speed. Any complete graphical method necessitates the 
use of a graduated circle or protractor at either end of a 
scaled base line. Two of the graphical methods are 
adaptations of the single-theodolite plotting board, one of 
which involves the permanent alteration of plotting 
board, while the other, and that favored most, brings 
about only a temporary alteration of the board. 

Method II. (1). Double-theodolite, graphical method. — The 
first of the above-mentioned schemes has been explained 
fully in the Monthly Weather Review for April, 1919, 
page 222. WTiere all double- theodolite work is over one 
base line, or all base lines of a station are of the same 
length, this scheme is very satisfactory, but it is not well 
adapted to stations having a system of base lines of 
varied lengths, for, as the length of the base line varies, 
so must the scaled distance AB vary in proportion, and 
this variation is difficult to accomplish on a single- 
theodolite plotting board as it is now arranged, with its 
fixed center. However, tlie radial lines from station B 
might be drawn upon tracing paper, and a slot prepared 
along the 0°-180° line to receive the protractor pin and 
allow for adjustment of base-line length, but this is un- 


satisfactory, since much difficulty will be experienced in 
placing the auxiliary sheet and keeping it in place over 
the fixed millimeter paper. Unless the base line is laid 
off to comparatively small scale, the method will not pro- 
vide for long runs, since it is difficult to alter the scale 
distance of the base line. Again, if the base-line scale is 
small, there will be considerable difficulty in plotting 
points and measuring velocities and directions for ascen- 
sions during periods of little wind movement. 

For the above reasons the following method is given 
as the simplest and most applicable graphical method to 
be used with the single-theodolite plotting board. This 
method can be used for a base line of any bearing and 
any length vfithin the limits of the distance scale on the 
protractor. The length of the base line may be changed 
or the scale of the same base line may be increased or 
decreased at will. 

Method II. {2 ) . Double-theodolite, graphical method. — The 
preparation of the single-theodolite plotting board for 
double-theodolite observations necessitates the use of a 
brass arm, and a point so placed as to represent the 
location of secondary station with reference to bearing 
and distance from primary station. To accomplish the 
location of this point, revolve the celluloid disk until the 
azimuth bearing of base line is placed over the index of 
the scale selected, then on that scale set a point at a 
distance from the center that will have a proper ratio to 
the distance from the secondary to the primary station. 
This point wdll mark the position of the secondary sta- 
tion, or station B. Place the brass arm over the central 
pivot, and the preparation is complete. As an example, 
let the horizontal projection. A, 1, 2 . . . . 10, 11, figure 
45, be the representation of data for double-theodolite 
observation on Form No. 1110-Aer., Table 20. Note 
that the line AB is in the direction from A, of 122°. 55, 
and that B is a point on that line a scale distance of 
1,781.86 meters from A. For purposes of explanation, 
let N-S be the north-south line through the secondary 
station, or that just located. 

To use the protractor, and to plot these data, let the 
center of the celluloid disk, figure 45, be the primary sta- 
tion, or station A, and the auxiliary point be the second- 
ary station, or station B. The data from both stations 
must be reduced to the same origin of orientation points. 
For graphical plotting, both tlieodolites should be ori- 
ented with the zeros of base plates on north. Keep in 
mind the fact that all azimuth settings for station B will 
be made by rotating the celluloid disk until that setting, 
on its edge, is placed over the index of the scale selected. 
For a direction of north, south, or any other direction at 
station B, will be parallel, so far as this work is con- 
cerned, to the same dij-ection at station A. Therefore 
the point A with its circumscribed arc of 360° may bo 
used for setting any direction at station B. All azimuth 
settings at station A will be made with the beveled edge 
of the brass arm pivoted at the center of protractor. 

To construct the horizontal projection for the data 
recorded on Form No. lllO-Aer., Table 20, rotate the 


INSTRUCTIONS FOR AEROLOCUCAL OBSERVERS. 


83 


colluloid disk until tlie azimuth reading at B, 314°. 3, is 
set over tlie index of scale 2-d, and set the edge of the 
brass arm on the azimuth reading at A, 43°. 5. Then, 
noting the position of point as located on protractor, 
pass an imaginary line through this point and parallel 
to the scale base or index of scale, letting it intersect the 
edge of the brass rule. At this point of intersection, place 
a point and set off by circle or cross. This last point 
fixed is the relative horizontal position of the balloon, 
and should be numbered as 1, 2, 3, etc. Proceed in the 
same manner with the remainder of the observation. 

The fifth point in the horizontal projection A, 1, 2 
. ... 10, 11, figure 45, illustrates the principle involved. 
In the actual construction of this particular horizontal 
projection, the disk was turned through a half circle; 
that is, all of the points as plotted fell within the semi- 


observed azimuth reading at A on the edge of the cellu- 
loid protractor. An imaginary lino is then passed through 
the point B, parallel to the line AU. Where this line 
intersects the edge of the brass rule, a point is placed, 
and designated as 5, which is the relative position of the 
balloon on a horizontal plane, for the fifth minute. As 
a proof of the setting for station B, let an imaginary line 
be drawn through A, cutting the circumference at 0° and 
180°, and let the line DA be produced through A to cut 
the circumference at M, and intersect the line N-S, at P. 
The angle 0°AM, then, is equal to angle PB5, for two 
angles whose respective sides are parallel are equal. 

Method II. (3 ) . Double-theodolite, graphical method . — 
The third graphical method of plotting necessitates the use 
of a large drafting board, table, or flat-top desk, iipon 
which the base line is laid out to some convenient scale. 



4(1. — I’lan of double-theodolite plotting board. 


circumference MOD, and not in the semicircumference 
DRM. Most of these points fell within the quadrant 
CFD, rather than quadrant RYM, as represented in 
figure 45. But to represent these two horizontal pro- 
jections upon the same figure without interference with 
one another, and yet to show the principles of each, and 
allow for comparison, the details of plotting tlie fifth 
point are laid out in quadrant RYM. When plotted, it 
fell in the same relative position in (juadrant CFD. To 
gain a clear impression, reverse figure 45. 'Phe hori- 
zontal projection will then appear as it did in quadrant 
CFD, upon the plotting of the fifth point. 

The observed azimuth reading for the fifth minute 
at B is 45°. 1, which was located on the edge of the pro- 
tractor and brought over the index of scale 2-d at D. 
The beveled edge of the brass arm is then set at 81°.6, the 


and the observation points marked by inserting pegs to 
protrude above the surface of the board. About those 
pegs and upon semicircles circumscribed about them 
play a set of arms, by moans of whicli the relative posi- 
tion of tlie balloon is found, and the distance away and 
elevation of balloon measured. Figure 4G represents 
such a plotting board. AB is the base lino, 1,200 meters 
long, laid out to the scale 1 cm. = 200 rn. CKF and 
EKD are graduated semicircles described about the 
observation points A and B, respectively. AK is the 
azimuth arm and elevation apparatus at station A, 
while BG is the azimuth arm at station B. The eleva- 
tion apparatus at station A consists of an arc of 90°, KL, 
fixed at the extreme end of the azimuth arm AK. About 
the post A, and playing upon this arc KL, is the elevation 
arm Kli. Still a fourth arm, or elevation scale PM, is 


84 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


attached perpendicularly to the azimuth arm AK. This 
bar is graduated to the same scale upon which AB is laid 
out. A cursor, or runner N, indicates the elevation of bal- 
loon at each minute when all settings are correctly made. 

As an example of the operation assume that the fol- 
lowing data are obtained when the theodolites are set up 
by the method of base-line orientation, which is the most 
convenient orientation for this system of graplhcal 
plotting. Let the azimuth and elevation angles at 
station A, be 70° and 25°, respectively, and the azimuth 
angle at station B be 120°. To locate the points, set the 
arm AK on 70° of the arc CKF, and the arm BG on 120° 
of the arc EK.D. It will be noticed that each of the 
azimuth arms is so constructed that a line along one 
edge would pass directly through the point about which 
it is placed. At the intersection of these edges a point 
will locate the horizontal position. Retaining the arms 
in this position, set the elevation arm AH on 25° of the 
arc KL, and set the elevation gage, PM, so that the right 
angle on the inside edge is coincident with the point of 
location. Finally, slide the runner to the position of N, 
or to the point of intersection of elevation arm and 
elevation gage. The position of the index along the 
graduated bar PM will give the elevation of the balloon, 
and the position of the index along the arm AK will give 
the distance out. The best application of this method is 
for stations provided with only a single base line. Where 
observation work is done over more than one base line, 
especially when these base lines are of varied lengths, 
additional posts will have to be set and semicircular arcs 
be drawn for each scaled length of each base line. 

Method 11. (4) . Douhle-theodolite, logarithmic method . — 
This method of computation is used more extensively in 
double-theodolite computation than in single. To facili- 
tate ease and accuracy of the work, the theodolites 
should be oriented by the base-line method. The 
principal of the computation is the sine formula in case 1^ 
of trigonometric computation of triangles, wherein we 
have given one side and two angles, figure 47. At 
stations with well-selected base lines nearly all the com- 
putation can be worked with the formulae — 


j b sin B 

CL — — 5 jTi 

sin U 

and h = d tan e; 

wherein h = base-line length. 

A = azimuth angle at station A. 
7i = azimuth angle at station B. 
(7=180°-(A+R). 
d = distance from station A. 
d' = distance from station B. 

^ = altitude of balloon. 
e = elevation angle at A. 
e' = elevation angle at B. 


(4) 

(5) 


Even with the most carefully selected base lines, 
instances will arise in which the balloon movement will 
be in a vertical plane nearly over and parallel to the base 


line. At such times, even though all angles during the 
observation are read to hundredths of degrees, they will 
not be close enough to avoid considerable error in 
the computation. To overcome this error as much 
as possible, the order in which the d and h factors are 
generally computed will be reversed, and the computation 
will then follow after one of the following pairs of 
formulae: 


and 




b tan e sin B 
sin {A +B) 


( 6 ) 


d = 


h 

tan e 


(7) 


or. 


^ b tan e tan e' 
~ tan e ± tan e' 


(8) 


and No. (7) above. That is to say, the value of h will be 
computed by formula (6) or (8), and from the result ob- 
tained d will then be found by formula (7). Formulae (6) 
and (7) will be used when the balloon is within an angle of 
4° to 10° from base line at station A, and formulae (8) and 


(7) will be used for angles from 0° to 4°. 

For angles of any 

other magnitude the formulae (4) and (5) may be used. As 
an example of the application of each method, let the fol- 
lowing data be computed by each pair of formulae. The 
letter in parentheses after each line of the example will 
designate the order in which it has been found best to 
work the problem to save the most time and acquire the 

greatest accuracy. 


Assume the elevation angle and the azimuth angle at 
station A to be 41°. 3 and 172°. 65, respectively, the cor- 

responding angles at station B to be 49° 

.0 and 10°. 42, the 

theodolites oriented by the base-line 

method, and the 

base line to be 1,781.86 meters. See figure 47. When 

the problem is computed by formidse 
have: 

(4) and (5), we 

log 5 = 3.25088 

(a) 

+ log sin 5 = 9.25721 

ib) 

2.50809 

(e) 

— log sin 0 = 9.48450 

(c) 

log d = 3.02359 

(/) 

+ log tan e = 9.94375 

id) 

log /i, = 2.96734 


5- = 927.58 meters {h) 
d= 1055.8 meters (i) 

by formulae (6) and (7) wo have: 


log 5 = 3.25088 

(fl) 

+ log sin 5 = 9.25721 

(5) 

+ log tan c = 9.94375 

(c) 

2.45184 

(e) 

— log sin (A + 5) =9.484.50 

id) 

log /i = 2.96734 

(/) 

+ log tan 6 = 9.94375 

(c) 

log d = 3.02359 

C<7) 

d= 1055.8 meters (5) 

/t = 927.58 meters (i) 


INSTRUCTIONS FOR AFROLO(}ICAL OBSERVERS. 


85 


and by formula) (8) and (7) wo have: 


log & = 3. 25088 

(a) 

-t-log tan e = 9. 94375 

ih) 

+ log tan e' = 0. 06084 

ic) 

3. 25547 

ie) 

— log (tan tan e') =0. 30726 

id) 

log 7^ = 2. 94821 

(/) 

— log tan e = 9. 94375 

(h) 

log d = 3. 00446 

(g) 

d = 1010. 3 

meters (h) 

h = 887. 58 

meters (i) 

tan e = 0. 87852 

id,) 

tan e' = 1. 1504 

id^) 

tan e + tan e' = 2. 02892 

ids) 

log (tan e + tan e') = 0. 30726 

id) 


a difrorcnco in results will appear by working the same 
data with the two pairs of formube. Such differences 
when present appear in problems of azimuth angles less 
than 10°. Computations by the two pairs of formulse on 
angles greater than 10° agree so closely that the compu- 
tation will be done by the formulae (4) and (5), these 
being the simpler. 

When the logarithmic computation has been completed, 
the data are then plotted in the same manner as for a 
single-theodolite observation. A great deal of care 
should always be given to the plotting operation, for if 
this is done in a careless manner the data resulting there- 
from will be considerably in error, and sometimes worth- 
less. 

The horizontal projection will nearly always be a 
smooth, even curve, though decided bends and shard 





47. — Plan of trlangulatlon showing relative positions of balloon at P when balloon is between ends of base line, and at P' when balloon is beyond either end of base line. 


It will be noticed that the values of d and Ji determined 
by these formulae do not agree with the values obtained 
f)y the use of the two preceding pairs of formulae. It 
must be taken into accoutit that formulae (8) and (7) use 
only the elevation angles for finding the altitude of bal- 
loon, and therefore the altitude, or h, factor would be 
the altitude of balloon were it in the vertical plane pass- 
ing through the base line. For this reason formube (8) 
and (7) should be used only when the azimuth bearing 
of balloon is quite small, within 4° of base line. The 
results by the first two pairs of formulae agree closely; in 
this case they are identical. But when the azimuth 
angles are small — that is, when the balloon is only a 
small angular distance from the direction of base line — 

« When tho balloon Is between the extremities of the base line, as at P, flKtire 47, the 
sum of tho tangents will bo used, and when tho balloon Is beyond either extremity of 
the base line, as P', figure 47, tho diflerenco of the tangents will be used. 


angles often exist. Tho difference between an actual 
bend of projection, even though it be sharp, and a waver- 
ing of projection due to poor data can generally be de- 
tected. In tho single theodolite plot A, 1, 2 . . . .21, 
22, figure 45, tho decided bend in projection at 8 to 10 
minutes is well founded, but point 13 seems to be out 
tho least bit. A smoother projection would bo made 
were tho point placed more nearly in lino with the 
eleventh, twelfth, and fourteenth points. Likewise the 
twentieth point seems to be out decidedly. As a means 
of checking such points, refer to tho data and chock over 
tho angles by tho differences. Occasionally errors in 
reading angles will bo detected. Tho errors occur prin- 
cipally during hasty readings and are generally either 
5°.0 or 0°.5 in error. 4'ho frequency of errors of 2°.0 and 
0°.2 comes next in order. In the case of tho thirteenth 
point, increasing the elevation angle from 28°. 3 to 28°.8, 


86 


INSTKUCTIONS FOR AP^ROLOGICAL OBSERVERS. 


or by 0°.5, changes the distance out for the point from 
4,832 meters to 4,730 meters, which brings point 13 in 
the same general curve of points 11, 12, and 14. In a 
similar manner the curve would be smoothed along the 
eighteenth to the twenty-first minute. Seldom will an 
actual observation present such an irregular curve, and 
with the careful observer there will be little need for 
checking and corrections. Roughness of horizontal pro- 
jection is generally indicative of carelessness and error. 

6. REDUCTION OF DATA. 

The immediate result of the horizontal projection is to 
furnish us with a plan of the horizontal movement of the 
balloon throughout the period during which it was fol- 
lowed by the observer. On a very much smaller scale, 
each point represents the actual horizontal position of 
the balloon at the time when the angles were read on the 
theodolite. Now, then, since the balloon is traveling 
with the wind, both in direction and velocity, and since 
we have a scaled plan of the horizontal movement before 
us, to measure the wind velocity and direction it is only 
necessary to measure the velocity of movement and direc- 
tion of movement of the balloon from the scaled plan 
and substitute the movement of the balloon for the move- 
ment of the wind. Scales corresponding to d-\, d-2, d-4 
are supplied with the plotting boards for the measure- 
ment of the velocities. The direction is taken directly 
from the board in most cases, as will be explained. 

The wind data for any point or minute represent the 
mean and resultant of the conditions over a two-minute 
interval of time, extending from the beginning of the 
preceding minute to the end of the following minute, 
thus placing the minute in question between these limits. 
In using the wind velocity scales, particular attention 
must be given that the wind scale used is that corre- 
sponding to the scale upon which the plot was made. If 
the projection is constructed upon the scale of 1 cm.= 
200 m., then the wind scale of the same base should be 
used. In applying the wind scale always apply it to 
alternating points, or connect the points on either side of 
the one being measured, from 0 to 2, from 1 to 3, and 
from 2 to 4, etc. The zero of the wind scale will be placed 
on the earlier of the three points under consideration, 
and the graduated edge will then be adjusted until it 
coincides with the last of the three points. Note that 
the point being measured is the point between. At the 
point of coincidence between the set scale and the last 
of the group, the velocity for the intermediate point will 
be read off to tenths of meters per second. Thus, the 
reading of the velocity for the first, second, and third 
points will be read from the coincidence of points 2, 3, 
and 4, with the edge of the scale, when applied to the 
respective groups 0 to 2, 1 to 3, and 2 to 4, etc. As an 
example, the wind velocities measured from the single- 
theodolite horizontal projection A, 1, 2 .... 21, 22, 

figure 45, when measured by wind velocity scale 2-^, 
and applied from A to 2, 1 to 3, 2 to 4, etc., give velocities 


of 8.0, 8.6, and 11.3 meters per second, respectively. 
Figure 48 shows a section of the plotting board and a 
portion of ascension No. 2136, from Table 19, with the 
application of wind scale to the horizontal projection in 
measuring the velocity for the seventh minute. Note 
that the zero of the scale is coincident with the sixth 
point of the projection, while the reading of velocity 
measurement, 9.8 meters per second, is taken coincident 
with the eighth point along the edge of the scale. The 
figure also shows the placement of same points for the 
determination of direction, as will be explained later. 
If the horizontal projection is constructed by the graphical 
cosine method, the velocity of movement will be deter- 
mined at the same setting as that by which the direction 
is determined, using the centimeter divisions of the milli- 
meter paper as a scale. 

To determine the velocity for the last point, 22, since 
there is not a point placed beyond to mark the limitation 
of the succeeding minute, we may either place an auxil- 
iary point in a position which would approximately 
satisfy the character of the last portion of the projection, 
and measure as before, or we may apply the scale to the 
last minute interval, that is, from 21 to 22, and double 
the scale reading. This last scheme is sufficiently 
accurate when that part of the projection is nearly a 
straight line and the points are evenly spaced; but when 
even a general curve prevails, the auxiliary point should 
be placed. It is also used in determining the direction 
for the last point. 

Measurement of the wind direction is no more difficult 
than measurement of the wind velocity, though until 
thoroughly understood is more confusing. The direction 
to be determined, like the velocity, is the mean or result- 
ant direction from the point or minute in question, for 
the two-minute interval extending from the beginning 
of the previous minute to the end of the succeeding 
minute; thus, the direction of the wind for the first, 
second, third, etc., minutes will be the resultant direc- 
tion between the points 0 to 2, 1 to 3, 2 to 4, etc., respec- 
tively. 

To measure the resultant direction for point 1, it is 
only necessary to rotate the protractor until the points 
0 to 2 are on the same straight lino. For instance, set 
both of these points over the scale base or index line of 
scale, and read the direction in degrees from the edge of 
the protractor over the index of the scale. To deteriniTie 
the direction for succeeding minutes 2, 3, 4, etc., rotate 
the protractor until the preceding and succeeding points 
to that being determined arc arranged on the same 
straight line parallel to the scale base. That is, to 
measure the direction of point 2, arrange the ])oinls 1 
and 3 so that they are in the same imaginary line parallel 
to the index of distance scale. For point 3, arrange 2 
and 4 on the imaginary parallel line. Note that the 
later numbered minute is always toward the operator 
when determining these directions, otherwise the direc- 
tions will bo 180° in error. Read the direction of move- 


INSTEUCTIONS FOR AEROLOOICAL OBSERVERS. 


87 


mont in whole degrees from the edge of the protractor 
over the same index of distance scale as for the first 
minute. In general it may be stated, to find the wind 
direction for any one minute rotate the protractor until 
the adjacent points of horizontal ])rojoction on either 
side, with the latest numbered point of the group toward 
the operator, are directly over the scale base or a line 
parallel to the scale base and read the direction in degrees 
on the edge of the protractor coincident with the index 
line of the scale base. 

A south wind will be designated as 0°, west as 90°, 
north as 180°, and east 270°, etc. Since the balloon 
travels with the wind, it is nearly always moving away 
from the observer, and owing to the fact that angles of 
azimuth are read on opposite side of instrument from 
balloon, it has been found better to set the zero of base 
plate on north when orienting the theodolite for an 
observation. This is well borne out when determining 
the direction of wind movement from the plotting board, 
as described just above. When the theodohte has been 
oriented -with zero of base plate on north, the resulting 
direction of points will be read from index of scale base 
on the near edge of the board; but when the theodolite is 
oriented with the zero of base plate on south, then it will 
be necessary to read the direction from the opposite edge 
of the board and over the scale base produced, as at M, 
figure 45. Note that the latter is more diflBcult to accom- 
plish since the figures of the graduated celluloid disk arc 
inverted, while by the north orientation they appear 
directly in front of the operator and are right side up. 

As an example, the directions for points 1, 2, 3, etc., of 

horizontal projection A, 1, 2 21, 22, figure 45, were 

determined by rotating the celluloid disk until A and 2, 
1 and 3, 2 and 4, etc., were on the scale base AD, or a line 
parallel to AD, and the directions read at the index of the 
scale at D, to the nearest whole degree. Thus for the 
first minute wo get 222°, or the observed azimuth reading 
of point 2. For the second point, when points 1 and 3 
are placed on a line parallel to AD, we get 242°, read from 
edge of protractor over the same index of scale base at D. 
Had the theodolite been set up with the zero of base 
plate on south, then the directions would have been read 
from the opposite side of the board, otherwise there 
would have been an error of 180°. Figure 48 illustrates 
the arrangement of horizontal projection of figure 45, for 
the determination of the direction for the seventh point. 
Note that the points 0 and 8 are ai ranged on the same 
line pai’allel to the scale base AD. The direction of 
movement 197 is taken in whole degrees from the index 
of the scale at D of the figure. 

Some observers may prefer to apjdy the wind scale to 
points for velocity, then, using this as a straight edge to 
aid in arranging points on the line parallel to scale base, 
immediately determine the direction for the same minute. 
The ease of determination of the latter is gained only 
through the loss of time in changing from one system to 
the other. 


From a horizontal projection constructed by method 
/ {S) the cosine method, the direction and velocity of 
wind movement are determined at a single setting. The 
initial proc(idurc is identical with that for determina- 
tion of the wind direction alone by either of the first two 
methods given, but the setting of the celluloid disk for 
the point to be determined is not disturbed until the 
velocity for that point has also been determined. To 
accomplish the latter, the centimeter divisions on the 
millimeter paper are used as a velocity scale, the values 
of the divisions depending upon the distance scale used. 
Wliether the distance scale is d-l, d-2, or d-4, the centi- 
meter divisions of the velocity scale are equal to the 
magnitude of the distance used, divided by 200. Tliis is 
obvious from the fact that the distance-out scale is given 
in hundreds of meters per centimeter, and that velocities 
are measured in meters per second over a two-minute 
interval. Upon this principle where the centimeter 
divisions of distance-out scale are equal to 100, 200, and 
400 meters, the centimeter divisions on the millimeter 
paper, when used as a velocity scale, will be equal to the 
factors of 0.5, 1.0, and 2.0, respectively. While the 
celluloid disk is set for the determination of the direction, 
note the number of wdiole and fractional centimeter 
divisions along a straight line between the limiting points 
of the two-minute interval and parallel to scale base. 
Multiply the number so determined by the velocitv factor 
corresponding to the distance scale used; the result is 
the velocity in meters per second. Much care must be 
taken that the proper factor, 0.5, 1.0, or 2.0, is applied to 
the centimeter divisions. The disk is then rotated to 
the setting for the determination of the subsequent 
points and the same procedure followed throughout. 

Whether the plot be of a single-theodolite or a double- 
theodolite observation, the same method of determining 
the wind direction and velocity is used, so long as the 
horizontal projection is made upon the rotating pro- 
tractor. However, if the horizontal projection has been 
plotted by means of double arm and elevation apparatus, 
then it would have been necessary to apply a T square 
and protractor to the plot in order to determine the 
direction. 

As the observer determines and calls out the wind 
velocities and directions, the recorder will enter these 
data in their respective columns and spaces on Form 
No. 1110-Aer. It is well to call the fifth, tenth, etc., 
minutes as the observer comes to them in the determi- 
nation of velocity and direction. This will eliminate 
many errors and much annoyance which might bo ex- 
perienced at the end of a long observation when it is 
occasionally found that the data given are one or more 
minutes short of the tabulated data. Let the data in the 
direction and velocity column of Form No. lllO-Aer., 
Tables 19 and 20, be the residts determined in this 
manner from the tabulated data, and horizontal pro- 
jectioTis A, 1, 2 .... 21, 22, and A, 1, 2 ... . 10, 11, 
figure 45, respectively. 


88 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 


Next in order in reducing data will be the prepara- 
tion of Form No. 1115-Aer., or velocity and direction 
graph, from which the data to be telegraphed are derived. 
Various methods for plotting this graph have been 
devised. A simple apparatus which has proved to be 


tude scale and guide for the triangle. This scale is 
fastened only at each extreme end and is graduated for 
every 100 meters to coincide with the altitude lines of 
Form No. 1115-Aer. On the celluloid backing perpen- 
dicular to the edge of the altitude scale at the zero point 




Fiq. 48. — Section of plotting board, .showing setting of horizontal projection for determination of direction and velocity for thescvmlh point. 


both accurate and speedy is constructed as follows: 
It consists of an 11 by 13 inch clip board, upon which 
is mounted a celluloid or hard bristol-board backing C, 
figure 49. Along the left edge of the celluloid backing 
is fixed a strip of the same material E, to act as an alti- 


is drawn a horizontal lino to act as a base line in placing 
the Form No. 1115-Aer. on the board. A celluloid 
triangle is then graduated along one of the perpendicular 
edges to coincide with the principal divisions of the Form 
No. 1115-Aor. This when placed oti celluloid back. 


INSTRUCTIONS FOR AKROLOGICAL OBSERVERS. 


89 


with the other perpendicular side running along the 
edge of the altitude scale, affords a simple, accurate, 
and quick method of plotting both velocity and direction 
at the same setting for any one minute. 


arrange the Form so that the heavy lino at the bottom 
edge and the loft end of cross-section area are coincident 
with the right angle formed by the horizontal base line 
and the edge of the altitude scale on the board. While 



Fig. 49. -Graphing board for construction of Form No. 1116-Aer. (A, spring clip; B, clip board; C, hard coiiuloid surface riveted on clip board; V, Form No. Iil6-Acr. sot with 
zero altitude corresponding to zero on /^; K, altitude scale corresponding to horizontal lines on Form No. ni5-Aer., graduated to every 100 melers; celluloid triangle for 
setting at proper altitude; 0, direction scale corresponding to vertical lines on Form No. lU6-Aer. graduated to every 9 degrees). 


To use this graphing board, or to construct the velocity 
azimuth graph from the data recorded on Form No. 
11 10-Aer., place the Form No. 1115-Aer. on the graphing 
board with the left end of Form under the altitude scale; 


holding firmly in this jiosition, depress the spring clip 
A and allow the top edge of the Form to pass under this; 
when released this will firmly hold the Form in place. 
Apply the triangle with the graduated edge along the 


90 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


horizontal lines of the Form; and when the second per- 
pendicular edge is against the edge of the altitude scale, 
see that the main graduations on the triangle are coin- 
cident with those on the Form. 

To construct the graph, set the triangle at the zero 
elevation, and by means of the graduated edge plot 
the values of the velocity and direction for the surface 
conditions. Then move the triangle to the next level, 
150, 175, 200, etc., meters, or whatever it may be, and 


observation, the triangle was set at zero elevation and 
the surface velocity, 4.4 m. p. s., was plotted by placing 
a pencil point directly on the bottom line of the cross- 
section area. With the same setting of the triangle, 
the surface direction, NNE., was plotted. The tri- 
angle was then moved along the altitude scale until the 
horizontal edge was near the altitude for point 1, in this 
case 240 meters, and the velocity of 8.0 m. p. s. and the 
direction of 222° were then plotted directly on the 240- 


f'onn No. 1 1 1 &-Aer 



plot the values for that level. The remainder of the 
data for the observation will bo plotted in like manner. 
At each setting of the triangle, both velocity and direc- 
tion will be plotted for that level . In flights which extend 
over 7,500 meters in altitude, it will be necessary to 
construct another curve for the data above that level. 
See section 8 on the rendition of forms. 

The graphs for both single- and double-theodolite 
observations, on Form No. 1115-Aer., figure 50, were 
plotted by this method. For the single- theodolite 


meter line without moving the triangle. The data for 
3, 4, etc., minutes for the remainder of the observation 
were plotted in the same manner. Note that each 
vertical line of the form represents 0.2 of one meter per 
second on velocity curve, and 4^ degrees on direction 
curve. 

When all points have been plotted, a line is drawn to 
connect all points of the plot and join them in a smooth 
curve. Decided irregularities and bumps in either the 
velocity curve or the direction curve are to bo checked 


INSTRUCTIONS FOR AEROLO(iICAL OliSEiiVERS. 


01 


over by reference to data on Form No. 1110-Aer., to 
see that no error has been made in the computation or 
reduction. In the velocity curve of the single-theodo- 
lite graph, figure 50, a peculiar kink occurs at the eleva- 
tion of 600 meters. From the graph it appears that the 
point should be in line with the two on either side. The 
velocity curve is likely to be more irregular than the 
direction curve; in fact it may be said that the actual 
direction curve will nearly always be smooth, though 
the irregularities, when at all present, are generally 
very prominent. 

iYhen the results of the observation are to be tele 
graphed, the data will be taken from the graph for the 
specified levels, recorded in their respective spaces on 
Form No. 1116-Aer., Table 21, coded, and filed in the 
telegraph office. To code the message see section 7. 

In determining the wind for the various levels from 
Form No. 1115-Aer., figure 50, it will be noticed that 
each 250 meters in altitude is designated by one or an- 
other of the slightly heavier horizontal lines. These lines 
will act as an index for the required levels. The tele- 
graphic data will give both velocity and direction for 
the surface, 250, 500, 1,000, 1,500, 2,000, 3,000, and 4,000 
meter levels, and the maximum altitude when more than 
4,000 meters. To obtain these data from the Form No. 
1115-Aer., use the altitude scale at the left as a guide, 
and, where the respective curves cross these 250, 500, etc., 
meter level lines, read off the values corresponding to 
the scale to which the graph was plotted. The velocity 
will be taken off to the nearest whole meter per second, 
and the direction will be taken off to the nearest 16 com- 
pass points, N, NNE, NE, etc. Note that each of the 
heavier vertical lines of Form crossing the velocity curve 
represents 1 meter per second, while each of the heavier 
vertical lines of Form crossing the direction curve repre- 
sents one of the 16 compass points. 

With the completion of the telegraj)hic message these 
data, with a few additional levels, are likewise entered 
in their proper places on Form No. 1114 -Aer., Table 22, 
or the monthly tabulated summary. One sheet is used 
for the tabulation of the morning observations and a 
second is used for the tabulation of the evening observa- 
tions. Upon the completion of this tabulation work, en- 
tries will then be made on Form No. 1112-Aer., Table 23, 
Form No. 1113-Aer., Table 25, when such data occur, and 
Form Fo. 1111-Aer., Table 24, when so desired by the 


station official. For the rendition of these and other 
Forms see section 8. 

All Forms and material will then be filed in some con- 
venient place, well known to all the observing force in 
any manner concerned with the balloon work. At the 
conclusion of each week’s observations, Sunday a. m., to 
Saturday p. m., inclusive. Forms Nos. 1110-Aer., 1112- 
Aer., and 1115-Aer. will be mailed to the Aerological 
Division at the Central Office. Forms Nos. 1 1 13-Aer. and 
1114-Aer., for both a. m. and p. m., will be mailed at the 
end of the month. Form No. 1116-Aer. will not be 
mailed to the Central Office, but will be retained at the 
station. All Forms must be filled out completely as in- 
structed under section 8, and promptly mailed. Forms 
Nos. 1110, 1112, 1113, 1114, and 1115 Aer. should be 
made in duplicate, and the second copy kept on file at 
the station to provide against entire loss of data in the 
mails. 

[Form No. 1116- Aer.] Table 21. 


U. S. DEPARTMENT OF AGEICULT0EE, 'n’EATHER BUREAU. 

Pilot Balloon Telegraphic Summary. 

Ascension number, 2136. Date, July 10, 1920. Time, 8:26 a. m. 


Distinguish ing 
code word. 

Di.stinguishing 
time word. 

Even (ai). Sur- 
face. 

Odd (eo). 250 
meters. 

Even (ai). 500 
meters. 

Direc- 

tion. 

Veloc- 

ity. 

Direc- 

tion. 

Veloc- 

ity. 

Direo [ Veloc- 
tion. ity. 

Station. 

Washington. 

a. m. 10th 
Carbuncle. 

NNE. 1 4 

Biped. 

NE. I 8 

Deacon. 

ENE. i 9 

Diplomacy. 

odd (eo). 
1,000 meters. 

Even (al). 
1,500 meters. 

Odd (eo). 
2,000 meters. 

Even (ai). 
3,000 meters. 

Odd (eo). 
4,000 meters. 

Direc- 

tion. 

Veloc- 

ity. 

Direc- 

tion. 

Veloc- 

ity. 

Direc- 

tion. 

Veloc- 

ity. 

Direc- 

tion. 

Veloc- 

ity. 

Direc- Veloc- 
tion. 1 ity. 

NNE. 

Bogl 

10 

mli. 

NNE. 

Bibu 

10 

lous. 

1 

NW. 4 

Sealegs. 

WSW. 

Niml 

18 

)ose. 

WSW. 19 

Nobody. 

Maximum 

altitude. 

Even (ai). 
Maximum 
altitude. 

Clouds. 

Cloud altitude, 
m. 

Visibility. 

Direc- 

tion. 

Veloc- 

ity. 

1 

Amt.jKind. 

Dir. 

4,500 

Tuggers. 

WSW. 

Niiu 

hose. Cul)by,cir 

I 

W. 

W. 

uin. 

} 

Good. 

Seven. 


State of weather 

tTo be sent only in case of no run.) 


(Signed) 


Henry. 


92 


INSTEUCTIONS FOK AEEOLOGICAL OBSEEVEES. 

Table 22. 

[Form No. IIH-Aer.] 

U. S. DEPAETMENT OF AOEICUT.TUBE, WEATHER BUREAU. 

Wind Direction and Velocity (m. p.s.). 

Station (place of observation). Month, July, 1920. Base, 65.3 meters. Time, 8 a. m. 



Prepared by John Doe, assistant. 

Table 23. 


[Form No. 1112-Aer. ) 


U. S. DEPARTMENT OF AGRICULTURE, WEATHER BUREAU. 


Weekly Summary of Aerological Observations with Pilot Balloons. 


Station (place of observation). Week ending July 10, 1920. 



1 

a 


1 

o 

d 

o 

>• 






Ascension 

rate. 







<D 

Q 

o 

3 

*0 

B 

:3 

starting 

time. 

CD 

,c 

*o 

t-c 

'A 

£ 

o 

a 

s 

Disappearance 
due to — 

Mean diameter 

Weight. 

j Free lift. 

Total lift. 

Tables. 

Time-altitude 

curve. 

Tyiie of 
balloon. 

Temperature. 

Pressure. 

j Humidity. 

Sun. 

Predominant clouds. 





Min. 


cm. 


9- 


m.p.m. 

m.p.m. 


° C. 

mb. 

% 


Few A. St. NW.; few Cu. NW. 


2125 

8:30 a.... 

1 

12 


76.0 

35 

189 

224 

200 

6"Unc 

2.3.3 

1,004.4 
1,007. 1 

65 

Bright 

ip 

2126 

3:17p... 

1 

22 

Haze 

77.5 

37 

192 

229 

200 


6" red 

24.4 

39 

Bright 

1 Ci. NW.; 3 Ci. St. NW.; 2 
Ci. Cu. NW. 

fl 

2127 

8:18 a.... 

1 

20 

Distance 

74.0 

30 

183 

213 

200 


6" Unc 

18. .3 

1,012.5 

.59 

Bright 

None. 


2128 

3:16 p... 
8:26 a.... 

2 


Burst 

80.0 

45 

202 

247 

200 


6" red 

2.5.0 

1,011.9 

1,014.2 

39 

Bright 

2 Ci. St. W.; 2 Cu. NW. 

6 a 

2129 

1 

13 

A. St. Clds 

7.5. 5 

31 

184 

215 

200 


6" red 

19.4 

76 

'rhroiigh clouds. 

Few Ci. Cu. NW.; 8 A. St. 
WNW. 

6p 

7a . . 

21.30 

None 

21.31 

3:11 p... 

1 

12 

Eclipsed by 
clouds. 

77.5 

.32 

185 

217 

200 


6" red 

25.6 

1,011.7 

67 

Through clouds. 

5A.St. W. 

10 St. WSW. 

7p 

3:21 p... 
8:23 a 

1 

5 

Cu. cloud 

77. 5 

42 

198 

240 

200 


6" red 

31. 1 

1.001.7 

1.011.8 

.59 

3'hrough clouds. 
Bright 

7 Cu. WNW. 


2132 

2 

12 

Against Ci. Cu. . 

74.5 

30 

183 

213 

200 


6" Unc.... 

23,3 

65 

4 Ci. St. WSW. 


2133 

3:31 p... 
8:27 a.... 

1 

15 

76. 5 

:33 

193 

231 

200 


6" red 

26.7 

1,012.5 

50 

Bright 

2 Cu. W. 


2134 

1 

23 

Haze 

75.0 

30 

183 

213 

200 


6" Unc.... 

25.6 

1,014.9 

61 

Bright 

Few St. Cu. NW. 

Q n 

2135 

3:09 p . . . 
8:26 a.,.. 

2 

15 


73.5 

27 

179 

206 

200 


6" Unc 

31. 1 

1,013.6 

34 

Bright 

Few St. Cu. W.; 2 St. W. 

10 a 

2136 

1 

22 

Haze 

76.0 

38 

19.3 

231 

200 


6" red 

23.3 

1,017.9 

62 

Bright 

1 Ci. W.; 1 Cu. W.; 10 Ut. 
Haze 0. 

10 p 

2137 

3:07 p . . . 

1 

9 

Cloud 

76.0 

34 

188 

222 

200 


6" Unc 

30.0 

1,015.9 

39 

Through clouds. 

2 Cu. NE. 


Notes: 


lU TRICK Henry, Mfteorolofflst, 

Opicial in Charfc. 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


93 


[Form No. mi-Aor.l Table 24. 

U. 3. DEPARTMENT OP AORICULTURE, WEATHER BURKAtT. 

.'Station (place of observation). (76th meridian time.) 


Time, 8:26 a. m. Wind-Aloft Report. Date, July 10, 1920. 


Altitude. 

Direction. 

Velocity. 

Remarks. 

771. 


m. p. s. 



nne. 

4 


250 

ne. 

8 


500 

ene. 

9 


750 

ne. 

11 


1,000 

nne. 

10 


l'250 

nne. 

10 


1,500 

nne. 

10 


1,750 

nne. 

5 


2,000 

nw. 

4 


2,250 

wnw. 

10 


2,500 

wnw. 

12 


2,750 

wsw. 

15 


3,000 

wsw. 

18 


3,250 

wsw. 

13 


3,500 

wsw. 

13 


3;750 

wsw. 

16 


4,000 

wsw. 

19 


4)250 

w. 

20 


4,500 

wsw. 

18 







(Signed) Patrick Henbt, Meteorologist. 


[Form No. 1113-Aer.] Table 25. 

u. 3. department of aoricultdre, weather bureau. 

Monthly Report of Cloud Altitudes from Pilot Balloon Ascensions. 


Station (place of observation). Month, July, 1920. 


Date. 

Cloud type. 

Altitude. 

Direction. 

Velocity. 

Remarks. 

2 

Cu 

771. 

800 

s. 

771. p. $. 
10.0 

8:21 a. m. 

3 

St. Cu 

2,000 

2,600 

1,800 

wnw. 

16.4 

3:31 p. m. 

8:39 a. m. 

6 

A. St 

wnw. 

6.8 

10 

Cu 

n. 

0.2 

3:16 p. m. 

3:14 p. m. 

8:22 a. m. 

11 

St 

i;4oo 

sse. 

8.5 

12 

St 

'450 

sw. 

4.8 

15 

St. Cu 

2,200 

1,750 

w. 

9.5 

8:32 a. m. 

15 

Cu 

w. 

12.0 

3:50 p. m. 

8:34 a. m. 

17 

A. Cu 

2,000 

wnw. 

11.0 

18 

St 

300 

s. 

8.0 

8:17 a. m. 

18 

St. Cu 

1, 000 

ssw. 

10.2 

3:40 p. m. 

8:24 a. m. 

19 

St 

'600 

wsw. 

11.0 

19 

A. Cu 

3,800 

1,600 

wsw. 

16.0 

3:37 p. m. 

3:40 p. m. 

3:14 p. m. 

8:48 a. m. 

20 

Cu 

one. 

2.5 

24 

St. Cu 

1,100 

2,800 

sse. 

2.0 

25 

St. Cu 

w. 

9.1 



(Signed) Patrick Henry, 

Official in Charge. 

7. CODING THE MESSAGE. 


The greatest care must be exercised in coding the tele- 
graphic message and preparing an accurate legible copy 
for the telegraph office. Each telegraphic message will 
be a report of the observation for which it stands, and 
will regularly include in the order of mention, so far as 
available, the name of the station; time of observation, 
the wind velocity, and wind direction at the surface, 250, 
500, 1,000, 1,500, 2,000, 3,000, and 4,000 meter levels; 
the maximum altitude reached; the velocity and direc- 
tion of wind for the maximum altitude when this is 
greater than 4,000 meters; clouds in amount, kind, and 
direction; the cloud altitude when known, and the sur- 
face visibility. When an observation is not made due 
to low clouds, mist, fog, rain, snow, etc., such information 
will bo telegraphed in place of the regular message. 

For the pre.sent only the above-mentioned altitudes 
will be sent in the telegraphic message. The 4,000-meter 
altitude word, when that altitude is attained, will be the 
last word sent indicating wind direction and velocity. 


except when the maximum altitude is greater than 4,000 
meters, in which case the 4,000-motcr altitude word will 
bo followed by a wind word expressing the direction and 
velocity of the maximum altitude. The code words ex- 
pressing the wind conditions are divided into two classes: 
Class 1, words possessing the characteristic vowels a or i 
in the first syllable; class 2, those possessing the char- 
acteristic vowels e or 0 , in the first syllable. Class 1 is 
used for the even-numbered words in the message after 
the time word, namely, second,. fourth, sixth, and eighth 
words; class 2 for the odd-numbered words in the mes- 
sage after the time word, namely, third, fifth, seventh, 
and ninth. 

The complete coded message for an observation may 
be divided into four distinct sections: (1) Designation, 
(2) time, (3) wind data, and (4) miscellaneous data, as 
follows : 


Section. 

Signification. 

Characterized by — 

Order of 
word in 
message. 

(1) Designation. 

Station. 

Name of station sending 
message. 

First. 

(2) Time. 

Observation, a. m., p. m., 
or special. 

C or H, date and time 
word, or “Special 
eleven,” etc. 

Second. 

(3) Wind data. . . 

Velocity and direction at 
surface: 

250 meters. 

500 meters. 

1.000 meters. 

1,500 meters. 

2.000 meters. 

3.000 meters. 

4.000 meters. 

First syllable containing: 
a or i. 
e or 0 . 
a or i. 
e or 0 . 
a or i. 
e or 0 . 
a or i. 
e or 0 . 

Third. 

Fourth. 

Fifth. 

Sixth. 

Seventh. 

Eighth. 

Ninth. 

Tenth. 

(4) Miscellaneous. 

Maximum altitude. 
Maximum altitude wind 
data. 

Predominating clouds. 
Cloud altitude. 

Visibility. 

T words. 

Wind words in a or i. 

C words. 

T words. 

Numbers. 

Eleventh. 

Twelfth. 

Thirteenth. 

Fourteenth. 

Fifteenth. 


Section 1 will consist of the telegraphic name of the 
station from which the message is sent. Section 2 will 
signify the time of observation, whether regular a. m. or 
p. m. or special. When the observation, being tele- 
graphed, is the regular a. m. or p. m. observation one of 
the regular date and time words (commencing with C 
or 11) will bo used. If the observation is a special one, 
then the word expressing the hour nearest to which the 
observation was made with the word “Special” will 
replace the time and date word. Thus a special observa- 
tion taken at 10:40 or 11:25 would bo indicated in the 
message by the words “Special eleven,” instead of the 
C or // date and time word. Section 3 will consist of the 
wind data in code for specified levels. The number of 
the words in this section will vary to some extent with 
the length of the observation. The maximum number of 
words for this section is eight, and for observations for 
less than 4,000 meters in altitude will decrease accord- 
ingly. For instance, a message for an observation of 
1,600 meters in altitude would contain wind data for five 
levels only, that is, surface to 1,500-metor level inclusive. 


94 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


If, for any reason, data are not available at an interme- 
diate level, the word “Missing” ^vill be inserted in the 
proper place so as to preserve the regular sequence of 
coded words. This does not mean that “Missing” will 
be sent, for instance, for the 3,000 and 4,000 meter levels 
when the observation extended to only 2,000 meters. 
This information is conveyed by the absence of further 
data in that section, and by the word expressing the maxi- 
miun altitude. Section 4 will consist of code words for 
miscellaneous data. The number of the words in this 
section will also vary, but the first and last will always 
be present. The first word will give the maximmn alti- 
tude attained in the observation. When the maximum 
altitude is more than 4,000 meters, the maximum altitude 
word will be followed by a code word of class 1, or the 
even group, and will express the velocity and direction 
at that level. When there are clouds, the third word of 
this section will signify the amount, kind, and direction. 
When the altitude of the clouds is known, this coded 
information immediately follows. The last word of the 
coded message will express the visibility by number 
according to scale. Thus, dense fog 'will be expressed 
by the word “Zero,” poor by the word “Four,” indif- 
ferent by the word “Five,” etc. In many instances this 
last section will consist of only the first and last words. 
Frequently the maximum altitude word and the cloud 
altitude word will be identical. The cloud altitude word 
should not be given vmless the altitude of the cloud base 
has been definitely established. 

The code is formded on the principles of the regular 
Weather Bureau code, and ■with slight modifications, 
fulfills all needs completely. The significant letters B, 
D, F, G, M, N, E, and S have the same numerical value 
as in the regular code, such as: R = 10, D = 20, F=30, 
etc., the value between the even 10 values being denoted 
by the vowels u, a, e, i, and o, corresponding to 0, 2, 4, 
6, and 8, respectively, as in the regular code. In direc- 
tions, the significant letters, B, D, F, etc., are modified 
by significant vowels such that each letter denotes one 
or two directions according to the vowel that follows it; 
for example, Ba, and Be correspond, respectively, to the 
even and odd classes of vrords denoting north; and Bi, 
and Bo correspond, respectively, to the even and odd 
classes of words denoting north-northeast. 

Each wind word of the message, section 3, indicates the 
wind velocity and direction at a particular altitude. 
The position of the word and the character of the first 
syllable signify the altitude at which such data were 
observed. The first word of this section, taken from the 
even group of words, or class 1, the first syllable of which 
ends in either a or i, denotes the conditions at the surface. 
The second word of the section taken from the odd group, 
or class 2, the first syllable of which ends in either e or o, 
denotes the conditions for the 250-ineter level. Like- 
wise, the third, fourtli, fifth, sixth, seventh, and eighth 
words alternating from the odd group to the even group, 
designate the wind conditions for the succeeding levels, 
500, 1,000 meters, etc. 


The direction from which the wind is blowing is denoted 
by the first two letters of the first syllable of each of the 
wind words, and is recorded to the nearest one of the 
16 compass points. This first syllable is made up of 
one of the code consonants B, D, F, etc., followed by one 
of the four vowels a, e, i, or o. These vowels are divided 
into two classes, a and i in the first class characterizing 
the even group of wind words, or the surface, 500, 1,500, 
3,000 meter and maximum-altitude levels; e and o in the 
second class characterizing tlie odd group of wind words, 
or 250, 1,000, 2,000, and 4,000 meter levels. Let it be 
noted that wind wordg characterized by a and i, designate 
directions at the eight compass points, e. g., N., NE., E., 
etc., while e and o designate directions at the intermediate 
compass points, e. g., NNE., ENE., ESE., etc. The 


Ntrf/, 



Kio. 51. — Graphical representation of wind words of balloon code. ('I'he outer circU. 

is the oven-word code direction; the inner circle is the odd-word code direction.) 

accompanying diagram, figure 51, indicates the direction 
denoted by the various combinations of consonants and 
vowels in the first syllable of the wind word, for both 
classes of wind words. For example, a wind word begin- 
ning with Da indicates a wind from the northeast, iVi a 
wind from the west-southwest, and these two combina- 
tions would only be found in words of the first class of 
even-order words. A wind word beginning with Fe 
denotes a wind from the cast. Mo from the south-south- 
west, and these would only bo found in words of the 
second class or odd-order of words. 

A message properly made out will contain a succession 
of wind words alternately of class 1 (characteristic vowel 
a or i) and class 2 (characteristic vowel e or o). The 
wind words are divided into those two classes, which 
alternate in the message, for the reason that slumhl one 


INSTRUCTIONS FOR AEROLOGI(L\L OBSERVERS. 


96 


of thp wind words of tho mossnj?o bo omitted in trans- 
mission, the omission may be readily detected. 

The wind velocity, or rate of movement in meters per 
second, is denoted by the second syllable of the wind 
word, wherein the first consonant is immediately fol- 
lowed by a vowel. The numerical values of the con- 
sonants and vowels have already been explained. The 
various combinations of these consonants and vowels 
make it possible to express any velocity from 1 to 89 
meters per second. However, the code provides for a 
velocity up to and including 50 meters per second only. 
Should the telegraphic data include velocities greater 
than 50 meters per second, code words may be coined 
according to the above principles, to designate the actual 
velocities. 

The odd values of the velocities are expressed by the 
presence of the letter y in the word, which increases the 
even value of the velocity, as expressed in the second 
syllable, by 1. This is illustrated by the word “bathday,” 
expressing a velocity of 23 meters per second, while the 
word “bagdad” containing the same combination of con- 
sonant and vowel, da, expresses a velocity of 22 meters 
per second, the direction in each case being from the 
north. A velocity of 1 meter per second is expressed by 
a word whose second syllable contains the letter y, but 
which has no other translatable value; thus, the word 
“daily” expresses a velocity of 1 meter per second from 
the northeast. When the velocity is less than 0.5 meter 
per second, the word “us,” indicating calm, will be used. 

Maximum altitude, or the height at which the balloon 
is lost to sight, is given in an altitude word which immedi- 
ately follows the last wind word in section 3 of the mes- 
sage. The altitude is reported to the nearest 100 meters, 
and for this reason code words are given for each 100 
meters from 100 to 15,000. All of the altitude words, 
whether maximum altitude or cloud altitude words, begin 
with T and are followed directly by the vowel a, u, or y. 
Altitudes under 10,000 meters will be expressed by words 
beginning with Tu or Ty, and altitudes gi-eater than 
10,000 meters will begin with Ta. In the second syllable 
a consonant followed by a vowel indicates the altitude in 
hundreds and thousands of meters, the same numerical 
value being assigned to the respective vowels and con- 
sonants in this syllable as in the wind words. In tho 
altitude words, the odd value of the altitudes is indicated 
by a final s in the wonl. This increases tho even value 
of the altitude word by 100 meters. For instance, Bi 
in the second syllable of the altitude word denotes an 
altitude of 1,000 meters, but with the presence of the 
terminating s it denotes an altitude of 1,700 meters. Let 
the following examples set forth the principles outlined 
above: 

Tusks = 100 meters. Tiieksy = 8, 000 meters. 

Turcoman= 800 meters. 'tape =10, 400 meters. 

'I'url'y = 3, 000 meters. 'I'aljards = 1 1, 300 meters. 

Tylus = 3, 100 meters. 

The kind, direction, and amount of the predominating 
clouds will be coded in the word immediately following 


the maximum altitude wind word, with tho exception 
that where the maximum altitude is less than 4,000 
meters the cloud word will immediately follow the maxi- 
mum altitude word itself. This type of word always 
begins with the letter C. The second letter of the word 
characterizes the type of cloud according to the following 
scheme: 

Cu for cirrus, or cirro-stratus. 

Oa for cirro-cumulus, or alto-cumulus. 

Ce for alto-stratus. 

Ci for cumulus. 

Co for strato-cumulus. 

Ch for stratus. • 

^|,|for nimbus, or cumulo-nimbus. 

In the second syllable a vowel following a consonant 
indicates the amount of clouds observed, as follows: 

u or y=one tenth or less. 
a=two or three tenths. 
e=four or five tenths. 
i=six or seven tenths. 
o=eight, nine, or ten tenths. 


The consonant preceding this vowel gives the direction 
to the nearest one of the eight compass points, from which 
the clouds are moving, thus: 


b from north, 
d from northeast, 
f from east, 
g from southeast. 


m from south, 
u from southwest, 
r from west, 
s from northwest. 


Ordinarily only the predominating clouds will be 
included in the telegraphic message. However, when 
two or more types of clouds are equally distributed over 
the sky, a word for each type vdll be included in the 
message. When two or more kinds of clouds are re- 
ported, the directions reported will be those of the 
respective kinds; the amount reported will be the amount 
observed of each general type. 

No ascension . — In case no regular ascension is made, 
for any reason, such as rain, snow, sleet, mist, haze, fog, 
or smoke, etc., the message will be tiled in tho regular 
order as though the ascension had been made. Tho 
reason for no ascension, followed by the word “none,” 
will be substituted for the regular wind data of the 
message in section 3. Much of tho data in section 4 
will then necessarily be omitted, (doudiness will be 
expressed as usual, with the exception of rain, snow, 
sleet, and mist, when it will be omitted. If a successful 
ascension ecjuivalent to 250 meters in elevation is made, 
the state of the weather will not be reported, but the 
message will be sent in the regular form. By reference 
to sub.sequent portions of the code, there will be found 
little dilliculty in the coding of the message. When 
coded, the message should be carefully checked and veri- 
fied before submitting to the telegraph oflice. The 
observation on which it is based shoidd be made promptly 
and as nearly as possible, at the scheduled time, and the 
calculation of data should be accompli.shed as rapidly 
as accuracy will permit. It is important that tho mes- 
sage be sent as soon as possible after the observation has 


96 


INSTKUCTIONS FOR AEROLOGICAL OBSERVERS. 


been completed. Each station will be informed of the 
observations that are to be telegraphed and the message 
for these data must not be omitted whether an ascension 
has been made or not. 

Stations that are instructed to telegraph only one of 
their daily observations will file a message at the regular 
time whether or not a successful ascension is made. 
If an ascension is made, the data will be coded and 
telegraphed in the regular manner. If an ascension is not 
made because of “rain,” “snow” “low clouds,” etc., the 
message will give this information, followed by the coded 
data for the immediately preceding observation. If the 
latter was not made, the reason for its omission will also 
be stated. Each portion of the message will be preceded 
by the proper time word. 

The proper coding of a typical pilot balloon message is 
given below. The data enciphered in section 3 are those 
obtained in the single- theodolite proiection A, 1, 2 
.... 21, 22, figure 45. 


(Station) (Time) (Surface) (250) (500) (1,000) 

Washington Carbuncle Biped Deacon Diplomacy Bogbull 

(NNE 4) (NE 8) (ENE 9) (NNE 10) 


(1,500) (2,000) 

(3,000) 

(4,000) 

(Maximum altitude) 

Bibulous Sealegs 

Nimbose 

Nobody 

Tuggers 

(NNE 10) (NW4) 

(WSW 18) 

(WSW 19) 

(4,500) 

(Maximum altitude wind) (Cloud) 

(Cloud) 

(Visibility) 

Nimbose 

Cubby 

Cirrum 

Seven 

(WSW 18) 

(1 Ci. W) 

(1 Cu. W) 

(Good) 


The enciphered data of the double theodolite observa- 
tion obtained from the projection A, 1, 2 .... 10, 11, 
figure 41, will appear as follows: 

(1) (2) (3) (4) (5) (6)_ 

(Station) Camber Naked Novity Rancourously Rebanish 

(7) (8) (11) (13) (15) 

Rabate Redbird Tyndall Control Six 

Due to the fact that the length of the observation was 
insufficient to provide data for more than the 2,000- 
meter level, a full 15-word message can not be submitted. 
Note that the words (9), (10), (12), and (14) are omitted. 

A message, filed from a station regularly telegraphing 


only one daily observation, but reporting the current 
and preceding observations, when the former has resulted 
in failure, will take the following form: 

(1) (2) (3) (15) (2) (3) (3) (15) 

Ithaca Coach Raining Four Hold Raining Foggy One 

The complete code used in telegraphing pilot-balloon 
observations is given in the following pages. 


CODE FOR TIME AND DATE WORDS. 


Date. 

A. M. 

P. M. 

1 

Coach 

Hold 

2 

Canvas 

Hazard 

3 

Collar 

Holland 

4 

Cave 

Hale 

6 

Cobble 

Hockey 

6 

Calico 

Hacking 

7 

Colic 

Hoodwink 

8 

Cavort 

Halcyon 

9 

Colon 

Hollow 

10 

Carbuncle 

Hamburg 

11 

Combustion 

Hobby 

12 

Cabal 

Hatband 

13 

Cobalt 

Hopback 

14 

Camber 

Habeas 

15 

Corbet 

Hombeak 

16 

Cabin 

Habit 

17 

Combine 

Hombill 

18 

Caboose 

Harbor 

19 

Cockboat 

Hobo 

20 

Caducean 

Handy 

21 

Conduct 

Honduras 

22 

Cadaver 

Halfday 

23 

Cordage 

Houdah 

24 

Cadet 

Hades 

25 

Code 

Hoiden 

26 

Caddie 

Hading 

27 

Codicil 

Hoarding 

28 

Candor 

Haddock 

29 

Condole 

Hoodoo 

30 

Capful 

Harmful 

31 

Coiffure 

Hogfur 


(Ca=even dates, a. m, Ha=even dates, p. m.) (Co=odd dates, 
a. m. Ho=odd dates, p. m.) 

Note. — In date words in which the vowel in the first syllable is “o,” 
the value of the second syllable is increased by one (1). 


97 


INSTKIK'TIONS FOK 


AFI{()L()(;i(\VL OBSFKVERS. 


CODE FOR WIND Al.OFT REPORT. 


NORTH. 


NNE, 


Class 1 (ovpii) words. 
Altitudes; 0, 500, 1,500, :$,00(). 


Class 1 (oven) words. 
Altitudes: 0, 500, 1,500, 3,000. 


7H. p. S. 

1 

Balky. 

7)1. p. S. 

26 

Bandit 

7tl . p. S. 

1 

BiUy 

?n. p. s. 

26 

Bildiment 

2 

Bacca 

27 

Bandily 

2 

Biparous 

27 

Bidingly 

3 

Bavaroy 

28 

Bandon 

3 

Bicavity 

28 

Bidon 

4 

Bachelor 

29 

Bandory 

4 

Biped 

29 

Bidogyn 

5 

Barley 

30 

Bagful 

5 

Biweekly 

30 

Bifurcate 

6 

Bacillus 

31 

Banfuily 

6 

BiUing 

31 

Bifuzzy 

7 

Baycliff 

32 

Bafak 

7 

BiUary 

32 

Bifacial 

8 

Bacon 

33 

Badfairy 

8 

Billow 

33 

Bigfay 

9 

Balconv 

34 

Barfee 

9 

Bijoutry 

34 

Biferous 

10 

Backbur 

35 

Baffetay 

10 

Bibulous 

35 

Biferey 

11 

Banbury 

36 

Baffin 

11 

Bibulously 

36 

Bifilar 

12 

Barbara 

37 

Ban'ishy 

12 

Biba.sic 

37 

Bifixity 

13 

Backbay 

38 

Bamfork 

13 

Bibacity 

38 

Biforine 

14 

Babel 

39 

Backfoyer 

14 

Bibber 

39 

Bifogy 

16 

Bayberry 

40 

Baguette 

15 

Bilberry 

40 

Bitguard 

16 

Babish 

41 

Eadguy 

16 

Bitbinder 

41 

Bigguy 

17 

Baybinky 

42 

Bargain 

17 

Bibbitary 

42 

Bigamist 

18 

Backbone 

43 

Baygate 

18 

Bilbo 

43 

Bigamy 

19 

Bathboy 

44 

Banger 

19 

Bigboy 

44 

Biggest 

20 

Baldus 

45 

Badgerly 

20 

Billduck 

45 

Bigeyed 

21 

BayduU 

46 

Banging 

21 

Bidumpy 

46 

Biggin 

22 

Bagdad 

47 

Baggily 

22 

Biddable 

47 

Bigilpey 

23 

Batbday 

48 

Bagoas 

23 

Birthday 

48 

Bigot 

24 

Baden 

49 

Baggory 

24 

Bidder 

49 

Bigotry 

25 

Badenfiy 

50 

Barmuck 

25 

Bindery 

60 

Bismuth 


(’lass 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


p. s. 

1 

Bevy 

in. p. 8. 

26 

Bedim 


in. p. s. 

1 

Boldly 

m. p. s. 

26 

Boddice 

2 

Beware 

27 

Bedirty 


2 

Bogland 

27 

Bodily 

3 

Belady 

28 

Bedote 


3 

Bolary 

28 

Bordon 

4 

Beheld 

29 

Bedoughy 


4 

Bolero 

29 

Bodocity 

5 

Beaver 

30 

Befurred 


6 

Bowyer 

30 

Boastful 

6 

Bev/ilder 

31 

BeakfuUy 


6 

Bovine 

31 

Bokfury 

7 

Beybk 

32 

BefaU 


7 

Boligny 

32 

Boldface 

8 

Below 

33 

Befancy 


8 

Bologna 

33 

Bookfancy 

9 

Beworry 

34 

Befetter 


9 

Boycott 

34 

Boutt'e 

10 

Bedbug 

35 

Beltferry 


10 

BogbuU 

35 

Bofelty 

11 

Bedbuggy 

36 

Befit 


11 

Bondbuyer 

36 

Bonfii'e 

12 

Beanbag 

37 

Beficiary 


12 

Bobance 

37 

Bowfishy 

13 

Beyball 

38 

Before 


13 

Bombay 

38 

B oxford 

14 

Berber 

39 

Bendfoy 


14 

Bonbekir 

39 

Bofoxy 

15 

Bearberry 

40 

Beguile 


15 

Bogberry 

40 

Bogus 

16 

Berbice 

41 

Beguilingly 


16 

Bobbin 

41 

Boldguy 

17 

Bellbirdy 

42 

Bengal 


17 

Bobbislily 

42 

Bogardus 

18 

Benbow 

43 

Beggarly 


18 

BoboUnk 

43 

Boggarty 

19 

Bellboy 

44 

Beget 


19 

Bourbony 

44 

Bourgeon 

20 

Bedust 

45 

Bergerly 


20 

Boddum 

46 

Bogey 

21 

Bedu.sky 

46 

Begirdle 


21 

Bogduty 

46 

Bougie 

22 

Bedaub 

47 

Beggingly 


22 

Bondage 

47 

Boggify 

23 

Beanday 

48 

Begotten 


23 

Boundary 

48 

Bogota 

24 

Bedew 

49 

Begodly 


24 

Border 

49 

Bowgory 

26 

Bedewy 

60 

Bemuffie 


25 

Bouldery 

60 

Bomund 


4 032!)- -21— 7 


98 


lN8TliUCT10i\S FOU AEliOLOGlCAL OBSEKVEKS. 


NE. 


CODE FOR WIND ALOFT REPORT— Continued. 

ENE. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


m. p. s. 

Dally 

m. p. s. 

26 

Dandiness 

7n. p. s. 

1 

Dippy 

m. p. s. 

26 

Disdip 

2 

Dacapo 

27 

Dandify 

2 

Dilate 

27 

Didickey 

3 

Daylark 

28 

Daddock 

3 

Dilatory 

28 

Disdoes 

4 

Dauntless 

29 

Dadoxylon 

4 

Dice 

29 

Disdoily 

5 

Dacey 

30 

Darkfui 

5 

Dickey 

30 

Diffuse 

6 

Davit 

31 

Dayfue 

6 

Diligent 

31 

Diffusedly 

7 

DayUly 

32 

Dartfall 

7 

Disciplinary 

32 

Diffame 

8 

Dacort 

33 

Dayfairy 

8 

Dipolar 

33 

Disfamily 

9 

Daylost 

34 

Dafer 

9 

Diplomacy 

34 

Differ 

10 

Dabuh. 

35 

Dayfelony 

10 

Disburse 

35 

Differently 

11 

DarkbuUy 

36 

DafEsh 

11 

Digbury 

36 

Difficult 

12 

Daba 

37 

Daffishly 

12 

Dish ark 

37 

Diffidently 

13 

Dampbay 

38 

Daffodil 

13 

Dibasicity 

38 

Diff'oim 

14 

Dabber 

39 

Daflocky 

14 

Diabet 

39 

Difformity 

15 

Daubery 

40 

Daguerre 

15 

Dibberly 

40 

Disgulf 

16 

Daubing 

41 

Daygull 

16 

Disbind 

41 

Disgustedly 

17 

Dabistisy 

Dagsbora 

42 

Dagart 

17 

Disbindery 

42 

Digamouse 

18 

43 

Daygalley 

18 

Disbowel 

43 

Digalaxy 

19 

Daybook 

44 

Dangerous 

19 

Disbordy 

44 

Digest 

20 

Darkdull 

45 

Dangerfully 

20 

Didus 

45 

Dingey 

21 

Dawduffy 

46 

Dagging 

21 

DingduUy 

46 

Digit 

22 

Dardanelle 

47 

Dagiggly 

22 

Disdain 

47 

Digitately 

23 

Darkday 

48 

Dagonism 

23 

Didactyl 

48 

Dingo 

24 

Dander 

49 

Daggory 

24 

Diadem 

49 

Diagonally 

25 

Day deck 

50 

Damusa 

25 

Didelphyd 

50 

Dismusk 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s. 

Deadly 

m. p. s. 

26 

Dedicate 

m. p. s. 

1 

Dolly 

VI. p. s. 

26 

DodipoU 

2 

Decant 

27 

Dedicatory 

2 

Dockage 

27 

Dowdishy 

3 

Delay 

28 

Dedona 

3 

Doorway 

28 

Dodo 

4 

Deceit 

29 

Dedory 

4 

Dover 

29 

Dodoggy 

5 

Decency 

30 

Dearthful 

5 

Donkey 

30 

Doomful 

6 

Decipher 

31 

Defusedly 

6 

Docking 

31 

Doubtfully 

7 

Deviltry 

32 

Deface 

7 

Docity 

32 

Dogface 

8 

Deadlock 

33 

Defanatory 

8 

Dolonrite 

33 

Dogfamily 

9 

Decoy 

34 

Defeat 

9 

Dolorously 

34 

Doffea 

10 

Debutant 

35 

Defensoi’y 

10 

Dobule 

35 

Downferry 

11 

Denbury 

36 

Defiance 

11 

DoUbuggy 

36 

Dolfin 

12 

Debase 

37 

Deficiency 

12 

Dogbane 

37 

Dogflshery 

13 

Debasingly 

38 

Deform 

13 

Donbay 

38 

Dogfox 

14 

Deb el 

39 

Deformity 

14 

Dogbee 

39 

Dotfollery 

15 

Dewberry 

40 

Dengue 

15 

Dombey 

40 

Dogguard 

18 

Debited 

41 

Degumy 

16 

Doorbind 

41 

Dockgully 

17 

Debility 

42 

Degamish 

17 

Dobicy 

42 

Dogal 

18 

Debonair 

43 

Degaranty 

18 

Dogbolt 

43 

Doggayly 

19 

Deckboy 

44 

Degender 

19 

Doughboy 

44 

Dogged 

20 

Deduct 

45 

Degeneracy 

20 

Dogdull 

46 

Doggery 

21 

Deducibly 

46 

Deggins 

21 

Dotduly 

46 

Doggish 

22 

Dedalous 

47 

Degilpey 

22 

Dockdam 

47 

Doggishly 

23 

Dedactyl 

48 

Dego 

23 

Dogday 

48 

Dongola 

24 

Dedentian 

49 

Degotey 

24 

Doder 

49 

Dongory 

25 

Deadeye 

50 

Demulsion 

25 

Dodecagyn 

50 

Dortmund 


INSTRUCTIONS FOR AFROLOGICAL OHSFRVFRS. 


99 


CODE FOR WIND ALOFT REPORT— Oontinned. 


EAST. 


ESIC 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


Class I (even) words. 
Altitudes: 0, 500, 1,.500, 3,000. 


?)!. p. S. 

1 

Fancy 

7n. p. s. 

26 

Fading 

m. p. s. 

1 

Fiky 

7n. p. s. 

26 

Fiendish 

2 

Facade 

27 

Fadingly 

2 

Fiscal 

27 

Fiendislily 

3 

Fallacy 

28 

Fardon 

’3 

Filatory 

28 

Fido 

4 

Father 

29 

Fardory 

4 

File 

29 

Fixdoggy 

5 

Facety 

30 

Faithful 

5 

Fippenny 

30 

Fitful 

6 

Fakir 1 

31 

FarfuUy 

6 

Fixing 

31 

FiendfuUy 

7 

Facially 

32 

Fanfare 

7 

Filiety 

32 

Fishfag 

8 

Favor 

33 

Falfastly 

8 

Fico 

33 

Fibfancy 

9 

Falconry i 

34 

Farfetch 

9 

Filosy 

34 

Fife 

10 

Fabulous 

35 

Farferity 

10 

Ficksburg 

35 

Fifedity 

11 

Fabulously ' 

36 

Fairfield 

11 

Filbury 

36 

Fifield 

12 

Fabaceous 

37 

Falfishy 

12 

Finback 

37 

FiUfinny 

13 

Farbay 

38 

Fanfoot 

13 

Fieldbay 

38 

Firmfoot 

14 

Fabella j 

39 

FaUforty 

14 

Fiberless 

39 

Fiforay 

15 

Fabery 

40 

Fagundus 

15 

Fibbery 

40 

ITgure 

16 

Fabian 

41 

FatguUy 

16 

Fishbite 

41 

Figurantly 

17 

Fabingy 

42 

Fagan 

17 

Figbiddy 

42 

FUlgap 

18 

Fadboil 

43 

Fag ally 

18 

Fimboro 

43 

Fig ary 

19 

Fatboy 

44 

Fadge 

19 

Fillboggy 

44 

Fidget 

20 

Fardug 

45 

Faggery 

20 

Fiducial 

45 

Fidgety 

21 

Faydub 

46 

Fagine 

21 

Fiduciary 

46 

Figgist 

22 

Fandango 

47 

Fawngilly 

22 

Fidalgo 

47 

Figginy 

23 

Far day 

48 

Fagots 

23 

Fidairy 

48 

Figoal 

24 

Fade 

49 

Fagopye 

24 

Fides 

49 

Figgoody 

25 

Fadedly 

50 

Farmulate 

25 

Fidelity 

50 

Filmuck 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s. 

Feckly 

m. p. s. 

26 

Fendille 

m. p. s. 

1 

Folly 

m. p. s. 

26 

Folding 

2 

FeUable 

27 

Fedity 

2 

Forward 

27 

Fordity 

3 

Fellary 

28 

Fedora 

3 

Forway 

28 

Fordo 

4 

Feeble 

29 

Fedoddy 

4 

Force 

29 

Foddory 

5 

Feathery 

30 

Fearfun 

5 

Foley 

80 

Formful 

6 

Feline 

31 

Fearfully 

6 

Folio 

31 

FoolfuUy 

7 

Felicity 

32 

Feefam 

7 

Foliosity 

32 

Footfall 

8 

Feloid 

33 

Fewfalsity 

8 

Follow 

33 

Foxfairy 

9 

Felony 

34 

Feafer 

9 

Forlornly 

34 

Forfeit 

10 

Febus 

35 

Fellferry 

10 

Forbush 

35 

Fogferry 

11 

Fearbunny 

36 

Fers field 

11 

Forbuy 

36 

Forficula 

12 

Fearbabe 

37 

Fearfltty 

12 

Forbade 

37 

Fobfinely 

13 

FeUbary 

38 

Fenfowl 

13 

Forbarely 

38 

Fourfold 

14 

Fellbear 

39 

FefoUy 

14 

Forbear 

39 

Forfootedly 

15 

Penberry 

40 

Ferguson 

15 

Forbearingly 

40 

Fourgun 

16 

Febing 

41 

FelguUy 

16 

Forbidden 

41 

Foygun 

17 

Fewbiggy 

42 

Feugar 

17 

Forbiddingly 

42 

Forgave 

18 

Fenboat 

43 

Fegarcy 

18 

Forbore 

43 

Foxganiy 

19 

Feedboy 

44 

Felger 

19 

Footboy 

44 

Foge 

20 

Fenduck 

46 

Fegemetry 

20 

Fondulac 

46 

Forgery 

21 

Feyndunce 

46 

Fengite 

21 

Fonduly 

46 

Forging 

22 

Feudal 

47 

Fegility 

22 

Foldage 

47 

Forgivingly 

23 

Feudary 

48 

Fengower 

23 

Foxday 

48 

Forgotten 

24 

Federal 

49 

Feargodly 

24 

Folders 

49 

Forgoingly 

25 

Federacy 

60 

Femur 

26 

Fordedly 

60 

Foimula 


100 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


CODE FOR WIND ALOFT REPORT— Continued. 
SE. 


SSE. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


m. p. s. 


s. 

1 

Gainly 


m. p. s. 

26 

Gaddish 

m. p, s. 

1 

Gilpy 

m. p. s. 

26 

Giddiness 

2 

Galago 


27 

Gaddingly 

2 

Gila 

27 

Giddily 

3 

Gallantry 


28 

Gador 

3 

Giglay 

28 

Girdon 

4 

Galena 


29 

Gaydoily 

4 

Give 

29 

Gigdotty 

5 

Galley 


30 

Gaatful 

5 

Gilery 

30 

Ginfume 

6 

Galiot 


31 

Gasfumy 

6 

Gilian 

31 

Girthfumy 

7 

Gapingly 


32 

Garfall 

7 

Girlishly 

32 

Giffard 

8 

Gallop 


33 

Garfairy. 

8 

Gillote 

33 

Girdfarcy 

9 

Galloway 


34 

Gaffer 

9 

Giglotry 

j 34 

Girtfeld 

10 

Gadbush. 


35 

Gayfeather 

10 

Gibbus 

35 

Gigfeyn 

11 

Gaynburg 


36 

Gasfitter 

11 

Gibusly 

36 

Gilfillan 

12 

Garbage 


37 

Gayfiny 

12 

Gimbal 

37 

Girdfiimy 

13 

Gabatay 


38 

Gafol 

13 

Gilbakery 

38 

Gilford 

14 

Gaberdine 


39 

Gadfolly 

14 

Gibbering 

1 39 

Gilfoy 

15 

Garbelay 


40 

Gangue 

15 

Ginbeddy 

40 

Girdgup 

16 

Gambit 


41 

Gaygurgle 

16 

Gibier 

41 

Gipgulfy 

17 

Gaybine 


42 

Gargarize 

17 

Gibingly 

42 

Gigantic 

18 

Gambol 


43 

Garganey 

18 

Gibbons 

1 43 

Gingaly 

19 

Gaboy 


44 

Gage 

19 

Gibbosity 

44 

Ginger 

20 

Gadus 


45 

Gaugey 

20 

Gindump 

j 45 

Gingerly 

21 

Gaduiniy 


46 

Gaging 

21 

Gigdually 

i 46 

Gingival 

22 

Gardant 


47 

Gargily 

22 

Gildale 

1 47 

Gingingy 

23 

Gayday 


48 

Gargol 

23 

Gipdarky 

I 48 

Gigot 

24 

Gardening 


49 

Gargoyle 

24 

Gilder 

49 

GiUgoby 

25 

Gardenly 


50 

Gamut 

25 

Gigdecky 

50 

Gimmut 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s. 

1 

1 

Geliy 

m. p. s. 

26 

Gelding 

7n. p. s. 

1 

Godly 

711. p. S. 

26 

Gordian 

2 

Gelatine 

27 

Gendizzy 

2 

Gocart 

27 

Godify 

3 

Gelably 

28 

Gemdore 

3 

Goodpay 

28 

Gondola 

4 

Gehenna 

29 

Geardotty 

4 

Gopher 

29 

Gondolai’y 

5 

Geleemy 

30 

G erf 111 

5 

Gopey 

30 

Godful. 

6 

Gelid 

31 

Gemfury 

6 

G oiling 

31 

Godfury 

7 

Gelidly 

32 

Gerfalcon 

7 

Goblinary 

32 

Godfather 

8 

Gecko 

33 

Gemfancy 

8 

Golore 

33 

Godfairy 

9 

Gerholdy 

34 

G offers 

9 

Golory 

34 

Gofer 

10 

Geburah 

1 35 

Genfenny 

10 

Gobum 

35 

Goldfelly 

11 

Geltbuy 

36 

G elfin 

11 

Gotbusy 

36 

Goffish 

12 

Gebang 

37 

Gemfiiy 

12 

Goodbar 

37 

Goldftnny 

13 

Gebamy 

38 

Gessford 

13 

Gobangy 

38 

Goldfoil 

14 

Gebber 

39 

Gefozzy 

14 

Gobelin 

39 

Goforbay 

15 

Gembelfry 

I 40 

Gegum 

15 

Godberty 

40 

Gorgus 

16 

Getbid 

i 41 

Gemguiry 

16 

Gobbing 

41 

Gotguay 

17 

Gerbilly 

1 42 

Gewgaw 

17 

Godbilly 

42 

Gongar 

18 

Gemsbok 

43 

Gesgally 

18 

Goldbound 

43 

Gogaliy 

19 

Gadbony 

44 

George 

19 

Gobony 

44 

Gorged 

20 

Geddum 

45 

Geogenously. 

20 

Golddust 

45 

Gorgeously 

21 

Gemduly 

46 

Georgian 

21 

Gongduty 

46 

Goggin 

22 

Gendarme 

1 47 

Getgilpy 

22 

Goddard 

47 

Goldgildy 

23 

Gendarmory 

1 48 

Geldgold 

23 

Goddary 

48 

Gorgon 

24 

Genderless 

1 49 

Geogony 

24 

Golden 

49 

Goldgoby 

25 

Geodesy 

j 50 

Gemmush 

25 

Goldenly 

50 

Gomut 


INSTIUICTTONS FOR AFKOL()(;U’AL OHSFUVKRS. 


101 


CODE FOR WIND ALOFT REPORT— (^onfimiod. 

SOUTH. HSW. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


771. p. S. 

1 

Mashy 

2 

Macadam 

3 

Malay 

4 

Majestic 

5 

Macey 

6 

Making 

7 

Machinery 

8 

Major 

9 

Mahogany 

10 

MarbuU 

11 

Mawkbury 

12 

Marbach 

13 

Mackbay 

14 

Madbee 

15 

Maybe 

16 

Mabin 

17 

Maybird 

18 

Marlboro 

19 

Maybog 

20 

Manduke 

21 

Malmduchy 

22 

Madam 

23 

Maday 

24 

Maiden 

25 

Maidenly 


m. p. s. 


s. 


m. p. s. 


m. p. s. 

Minding 

26 

Madia 

1 

Micky 

26 

27 

Maddingly 

2 

Mica 

27 

Middingy 

28 

Madonna 

3 

Midway 

28 

Misdoubt 

29 

Mandory 

4 

Millet 

29 

Misdodgy 

30 

Marful 

5 

Miley 

30 

Mindful 

31 

Manfully 

6 

Midwinter 

31 

MightfuUy 

32 

Marfa 

7 

Military 

32 

Misfall 

33 

Madfay 

8 

Milo 

33 

Misfairy 

34 

Magfell 

9 

Milogy 

34 

Misfeign 

35 

Macfeely 

10 

Milburn 

35 

Milfelony 

36 

Maxfield 

11 

Misbury 

36 

Misfit 

37 

Mayfish 

12 

Milbach 

37 

Milfiggy 

38 

Malform 

13 

Midbaby 

38 

Misform 

39 

Maydfowl 

14 

Misbear 

39 

Misfoolery 

40 

Magus 

15 

Milberry 

40 

Misguide 

41 

Mainguy 

16 

Misbirth 

41 

Misguy 

42 

Margarite 

17 

Milbilly 

42 

Misgave 

43 

Margay 

18 

Misbom 

43 

Midgailey 

44 

Magenta 

19 

Midboy 

44 

Misget 

45 

Mangery 

20 

Misdude 

: 45 

Milgentry 

46 

Magic 

21 

Mixduly 

46 

MUsgiven 

47 

Magically 

22 

Mida 

1 47 

Misgiddy 

48 

Maggot 

23 

Midday 

48 

Misgovern 

49 

50 

Madgoying 

Mamugue 

24 

25 

Milden 

Mildewy 

49 

50 

Misgory 

Mamulus 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s. 

2 

3 

4 

5 

6 

7 

8 
9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 
26 


Mealy 

Medlar 

Melancholy 

Meeken 

Methenyl 

Mexico 

Melissyl 

Melon 

Melody 

MeantauU 

Medbury 

Mealbag 

Membarry 

Member 

Mealberry 

Membine 

Merbilly 

Melbourne 

Messboy 

Medusa 

Medullary 

Medal 

Meanday 

Meander 

Medeny 


s. 


m. p. s. 


m. p. s. 


26 

Medical 

1 

Monthly ' 

26 

Modius 

27 

Mediacy 

2 

Mackade 1 

27 

Modify 

28 

Meadow 

3 

Mohairy 

28 

Modoc 

29 

Mendosey 

4 

Mole 

29 

Modoci’y 

30 

Meanful 

6 

Monkey 

30 

Mournful 

31 

MeedfuUy 

6 

Molino 

31 

Morfurry 

32 

Medfast 

7 

MoUify ! 

32 

Moffat 

33 

Menfaggy 

8 

Mohocks 

33 

Morfarcy 

34 

Meanfelt 

9 

Moochooey 

34 

Moffette 

36 

Medfelly 

10 

Messbunker 

36 

Mossfelty 

36 

Medfield 

11 

Mossburly 

36 

Moorfish 

37 

MeanfiUy 

12 

Morband | 

37 

Moldfinny 

38 

Medford 

13 

Mossbay 

38 

Moorfowl 

39 

Menfoxy 

14 

Mobbed 

39 

Morfondly 

40 

Mergus 

15 

Moberly 

40 

Morgue 

41 

Mealgunny 

16 

Mobilize ! 

41 

MoguUy 

42 

Megapode 

17 

Mockbilly 

42 

Morgan 

43 

Megaionyx 

18 

Morbose j 

43 

Morgay 

44 

Merge 

19 

Mobocracy 

44 

Monger 

46 

Meagerly 

20 

Module 

46 

Morgently 

46 

Merging 

21 

Modulantly 

46 

Mogilno 

47 

Meangilly 

22 

Mordant 

47 

Mossgilly 

48 

Mergot 

23 

Monday 

48 

Mongolian 

49 

Mengoodly 

24 

Mode 

49 

Montgomery 

60 

Meanmug 

25 

Modesty 

60 

Momus 


’02 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


CODE FOR WIND ALOFT REPORT— Continued. 

sw. wsw. 


Class 1 (even) words. Claes 1 (even) words. 

Altitudes; 0, 500, 1,500, 3,000. Altitudes: 0, 500, 1,500, 3,000. 


m. j). s. 

\ 

Nancy 

m. p. s. 

26 

Nadir 

m. p. s. 

1 

Nightly 

m. p. s. 

26 

Niding 


2 

Nazarene 

27 

Naidinay 

2 

Nirvana 

27 

Nidify 


3 

Navally 

28 

Nandow 

3 

Nipay 

28 

Nidor 


4 

Naked 

29 

Nadobby 

4 

Niles 

29 

Nidorosity 


5 

Naively 

30 

Nailful 

5 

Nicely 

30 

Nigful 


6 

Narcissus 

31 

Natfumy 

6 

Niblic 

31 

NightfuUy 


7 

Napkinly 

32 

Nagfair 

7 

Nihility 

32 

Nightfall 


8 

Napoleon 

33 

Nafady 

8 

Nilod 

33 

Nifalcy 


9 

Nauscopy 

34 

Nafe 

9 

Niloscopy 

34 

Niflfert 


10 

NabuU 

35 

Natferry 

10 

Nimbus 

35 

Niffemy 


11 

Naybuif 

36 

Narfin 

11 

Nigbuy 

36 

Nightfire 


12 

Nailball 

37 

Nanfiggy 

12 

Niband 

37 

NiffiUy 


13 

Nabasye 

38 

Narford 

13 

Nibally 

38 

Nightfog 


14 

Nabbed 

39 

NafoUy 

14 

Niobe 

39 

Niffodly 


15 

Nabetony 

40 

NanguU 

15 

Nisberry 

40 

Nigua 


16 

Nabbing 

41 

Nagually 

16 

Nibbing 

41 

NiguUy 


17 

Nabilgy 

42 

Nagasaki 

17 

Nibbirdy 

42 

Niggard 


18 

Nabob 

43 

Nagany 

18 

Nimbose 

43 

Niggardly 


19 

Nanboy 

44 

Nagged 

19 

Nilbody 

44 

Niger 


20 

Nandu 

45 

Naggemy 

20 

Nidus 

45 

Nidgery 


21 

Nay dual 

46 

Nargil 

21 

Nidusly 

46 

Niggish 


22 

Nadab 

47 

Naggingly 

22 

Nidal 

47 

Nilgilly 


23 

Nabdaddy 

48 

Nalgonda 

23 

Nidary 

48 

Nightgown 


24 

Narden 

49 

Nagory 

24 

Nide 

49 

Nipgory 


25 

Nadecyl 

50 

Namur 

25 

Niddery 

50 

Nism’or 



Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s . . 

1 

N early 

m. ft. 

26 

Neddiness 


in. p. s. 

1 

N obly 

m. p. 5. 

26 

Nodding 

2 

N evada 

27 

Needily 


2 

Norval 

' 27 

Noddingly 

3 

Neyland 

28 

N ewdorp 


3 

Nopalry 

28 

Nodose 

4 

Nearness 

29 

Neadonary 


4 

Novel 

29 

Nodosity 

5 

N ecessary 

30 

Neckfur 


5 

Nocently 

30 

N onf ulfUl 

6 

Nervine 

31 

Needfully 


6 

Novice 

31 

NoyfuUy 

7 

N egligency 

32 

Nefarious 


7 

Novity 

32 

N ofar 

8 

N ervous 

33 

N efariously 


8 

Norwood 

33 

Nonfancy 

9 

N eckyoke 

34 

Neife 


9 

Novology 

34 

Nonfeance 

10 

Nebulous 

35 

Needfelly 


10 

Nobbut 

35 

Nonfedity 

11 

Nebuly 

36 

Newfield 


11 

Noybulb 

36 

Northfield 

12 

Nebat 

37 

N estfinny 


12 

Noback 

37 

Nonfldehty 

13 

N eahbay 

38 

Newfound 


13 

Nonbaby 

38 

Norfolk 

14 

Nebeb 

39 

Nefoamy 


14 

Norbeck 

39 

Nonfoxy 

15 

Nedberry 

40 

Negus 


15 

Nobelay 

40 

Noguera 

16 

N esbit 

41 

N egundory 


16 

Nobile 

41 

Noygust 

17 

Nebilly 

42 

Negative 


17 

Nobility 

42 

Nougat 

18 

N eighbor 

43 

Negatory 


18 

Noboat 

43 

Nogaray 

19 

N eighbor] y 

44 

Negget 


19 

Nobody 

44 

Nogent 

20 

N ewdime 

45 

Nelgentry 


20 

Nodular 

45 

Nongentry 

21 

Neyducat 

46 

Neginoth 


21 

Noyduct 

46 

Noggins 

22 

Nedar 

47 

Negirthy 


22 

Nodation 

47 

Nogiddy 

23 

Netdarky 

48 

Negotiate 


23 

Noonday 

48 

Nogo 

24 

Nedder 

49 

N ewgory 


24 

Nodded 

49 

Nongoodly 

25 

Newderby 

50 

Nemuel 


25 

Nodewy 

60 

Nomus 


INSTRUCTIONS FOR AFROLOGK^AL OBSP’JIVFRS. 


103 


CODE FOR WIND ALOFT REPORT-Oontinuod. 

WEST. WNW. 


Class 1 (evenl words. 
Altitudes: 0, 250, 1,500, 3,000. 


Class 1 (even) words. 
Altitudes; 0, 500, 1,500, 3,000. 


m. p. s. 


m. p. s. 


1 

Racy 

26 

Radiant 

2 

Rampart 

27 

Radially 

3 

Railway 

28 

Random 

4 

Rake 

29 

Rathdowny 

6 

Raillevy 

30 

Rashful 

6 

Racing 

31 

Rapfally 

7 

Racially 

32 

Rainfall 

8 

Racoon 

33 

Rainfarry 

9 

Rancorously 

34 

Raffed 

10 

Rambuse 

35 

Rackferly 

11 

Rawbundy 

36 

RaflBnose 

12 

Rabate 

37 

Rafl&ay 

13 

Rambady 

38 

Radford 

14 

Rabbeting 

39 

Rayfoily 

15 

Raspberry 

40 

Raguled 

16 

Rabid 

i 41 

Ranguly 

17 

Rabbitry 

1 42 

RagamufBn 

18 

Rawbone 

1 43 

Ragabashy 

19 

Ramboy 

44 

Raggedness 

20 

Radula 

45 

Raggery 

21 

Radulately 

46 

Raging 

22 

Radama 

47 

Ragingly 

23 

Randandy 

48 

Ragout 

24 

Raider 

49 

Ragouty 

25 

Radey 

50 

Ramusio 


m. p. s. 


m. p. s. 


1 

Richly 

26 

Ridicule 

2 

Riparian 

27 

Ridingly 

3 

Rivalry 

28 

Ridotto 

4 

Ripest 

29 

Ringdotty 

5 

Ripely 

30 

Rightful 

6 

Risking 

31 

Rightfully 

7 

Rickishly 

32 

Rightface 

8 

Richohet 

33 

Rigfally 

9 

Ridlory 

34 

Rifeness 

10 

Ribull 

35 

Rifelly 

11 

Ribbuoy 

36 

Richfield 

12 

Ribald 

37 

Rifibby 

13 

Ribandry 

38 

Rinford 

14 

Ribbed 

39 

Riforay 

15 

Ribbery 

40 

Rigum 

16 

Ribbing 

41 

Ringusly 

17 

Ribbingly 

42 

Rigadoon 

18 

Ribbon 

43 

Ribgalley 

19 

Ribbonry 

44 

Ridgeless 

20 

Ridum 

i 45 

1 

Riggerdy 

21 

Riftdungy 

i 46 

Rigid 

22 

Riddance 

47 

Rigidity 

23 

Ridably 

48 

Rigor 

24 

Riderless 

49 

Rigorously 

25 

Ridently 

50 

Rimula 


('lass 2 fodd ) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. 'p. s. 

1 

I 

Rely 

m. p. s. 

26 

Reading 

2 

Recall 

27 

Readily 

3 

Recarry 

28 

Redoubt 

4 

Reflect 

29 

Redolently 

5 

Recently 

30 

Refute 

6 

Recipe 

31 

Redfury 

7 

Recipiency 

32 

Refasten 

8 

Reflow 

33 

Realfairy 

9 

Reenjoy 

34 

Refer 

10 

Rebuff 

35 

Refectory 

11 

Rebury 

36 

Refining 

12 

Rebanish 

37 

Refinery 

13 

Reedbay 

38 

Reform 

14 

Rebelled 

39 

Refortify 

15 

Redberry 

40 

Regular 

16 

Redbird 

41 

Regularly 

17 

Redbindery 

42 

Regard 

18 

Rebound 

43 

Regally 

19 

Reembody 

44 

Regent 

20 

Reduced 

45 

Reagency 

21 

Redundancy 

46 

Region 

22 

Rendable 

47 

Registry 

23 

Reddaisy 

48 

Regorge 

24 

Redemption 

49 

Regorgify 

26 

Redely 

60 

Remus 


Class 2 (oddl words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


771. p. S. 

1 

m. p. s. 


1 

Ropy 

26 

Rounding 

2 

Roulade 

27 

Rodiya 

3 

Roadway 

28 

Rondo 

4 

Rover 

29 

Rodomonty 

5 

Rockery 

30 

Roomful 

6 

Roving 

31 

Rollfully 

7 

8 

Rockingly 

Rococo 

32 

33 

Roofage 

Rofairy 

9 

Roloway 

34 

Roofer 

10 

Roebuck 

36 

Rockferry 

11 

Robustly 

36 

Roofing 

12 

Roband 

37 

Rockfilmy 

13 

Rockbay 

38 

Rockfoot 

14 

Roadbed 

39 

Rollfoggy 

16 

Robbery 

40 

Rogue 

16 

Robins 

41 

Roguishly 

17 

Rockbibby 

42 

Rogation 

18 

Roborant 

1 43 

Rogatory 

19 

Rollboy 

44 

Roger 

20 

Rondure 

45 

Rogentry 

21 

Roydub 

46 

Rouging 

22 

Rondache 

47 

Rogimpy 

23 

Rodaily 

48 

Rockgoat 

24 

Rodent 

49 

Rogory 

26 

Roundelay 

60 

Romulus 


104 


INSTKUCTIONS FOR AEROLOGICAL OBSERVERS. 


NW. 


CODE FOR WIND ALOFT REPORT— Continued. 

NNW. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


Class 1 (even) words. 
Altitudes: 0, 500, 1,500, 3,000. 


m. p. s. 

Saucy 

m. p. s. 

26 

Sardine 


m. p. s. 

1 

Sickly 

m. p. s 

26 

Siding 

2 

Sacar 

27 

Sandily 


2 

Silvan 

27 

Sidinky 

3 

Salary 

28 

Sardonic 


3 

Sikay 

28 

Siddow 

4 

Save 

29 

Sardony 


4 

Silence 

29 

Sidoily 

5 

Saddlery 

30 

Sackful 


5 

Silently 

30 

Sinful 

6 

Savior 

31 

Sackfun-y 


6 

Silcilian 

31 

Sinfully 

7 

SaUency 

32 

Salable 


7 

Sickishiy 

32 

Sitfast 

8 

Saloon 

33 

Sacfancy 


8 

Sillock 

33 

Sinfancy 

0 

Sallov/y 

34 

Safeguard 


9 

Siloy 

34 

Simfeme 

10 

Sabula 

35 

Safety 


10 

. Sibiilk 

35 

Siffemy 

11 

Sabulosity 

36 

Saltfish 


11 

SickbuUy 

36 

Siffian 

12 

Sabbath. 

37 

Saffirey 


12 

Sitzbath 

37 

Sifilety 

13 

Sabbatlu'y 

38 

Sanford 


13 

Sib ary 

38 

Sixfold 

14 

Saber 

39 

Sanfoldy 


14 

Siberian 

39 

Sifony 

15 

Sagbelly 

40 

Sanguine 


15 

Sibbendy 

40 

Singular 

16 

Sabine 

41 

Sadguy 


16 

Sibilant 

41 

Singularly 

17 

Sabianry 

42 

Sagamore 


17 

Sibilancy 

I 42 

Singapore 

18 

Sambo 

43 

Sagacity 


18 

Sibboleth 

43 

Sigarety 

19 

Saboray 

44 

Sagenite 


19 

Sickboy 

44 

Singer 

20 

Sadducee 

45 

Sandgelly 


20 

Sidulate 

45 

Siggerly 

21 

Sandusky 

46 

Saginaw 


21 

Signduty 

1 46 

Singing 

22 

Sandal 

47 

Sagittary 


22 

Sirdar 

j 47 

SigiUary 

23 

Sadday 

48 

Sargon 


23 

Sib day 

! 48 

SiSgo 

24 

Saddest 

49 

Sagoinly 


24 

Sideral 

1 49 

Sigourney 

25 

Sanderay 

50 

Samuel 


25 

Sideway 

50 

Simulate 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


Class 2 (odd) words. 
Altitudes: 250, 1,000, 2,000, 4,000. 


m. p. s. 

1 

Seepy 

m. p. s. 

26 

Sedition 

VI. p. s. 

Soapy 

m. p. s. 

26 

Sodium 

2 

Sealark 

27 

Seditiously 

2 

Solar 

27 

Sordity 

3 

Secancy 

28 

Seldom 

3 

Soiary 

28 

Southdown 

4 

Sealegs 

29 

Seadotty 

4 

Solenoid 

29 

Sodomy 

5 

Secrecy 

30 

Seafur 

5 

Solemnity 

30 

Songful 

6 

Servile 

31 

Seafully 

6 

Solid 

31 

Soulfully 

7 

Sealily 

32 

Serfage 

7 

Sociably 

32 

Sofa 

8 

Seahog 

33 

Seafairy 

8 

Solon 

33 

Soulfalacy 

9 

Sepoy 

34 

Seafems 

9 

Socoury 

34 

Sofett 

10 

Seabum 

1 35 

Selferry 

10 

Soapbubble 

35 

SopfeUy 

11 

Sebundy 

36 

Seafish 

11 

Soyburg 

36 

Soflsm 

12 

Seabate 

37 

Selfishly 

12 

Sorbate 

37 

Sofinny 

13 

Sebaciously 

38 

Seafoam 

13 

Sobaly 

38 

Soulfoot 

14 

Seabean 

39 

SeafoUy 

14 

Somber 

39 

Sowfolly 

15 

Seaberry 

40 

Seagull 

15 

Soberly 

40 

Sogun 

16 

Seabird 

! 41 

Selfguy 

16 

Songbird 

41 

Soygurt 

17 

Seabilgy 

42 

Segar 

17 

Sobbingly 

42 

Southgate 

18 

Seaborne 

1 43 

Seagalley 

18 

Soboles 

43 

Southgary 

19 

Seaboy 

44 

Sergeant 

19 

Sobolery 

44 

Sorgen 

20 

Seduce 

45 

Sengelly 

20 

Sodupe 

45 

Sogery 

21 

Sedulity 

46 

Sedging 

21 

Soydux 

46 

Songish 

22 

Sedan 

47 

Seagirty 

22 

Sodainide 

47 

Sogify 

23 

Sedately 

48 

Seagod 

23 

Sodality 

48 

Sorgo 

SouTgoody 

24 

Sederunt 

49 

Seggony 

24 

Soldering 

49 

25 

Sedentary 

1 50 

Semuncial 

25 

Sordesy 

50 

Solmuth 


INSTRUCTIONS FOR AKROI.OCJKWL OBSFRVFRS. 


105 


CODE FOR ALTITUDE OF CLOUDS AND BALLOONS. 


m 


m 


m 


m 


100 

Tusks 

4,100 

Tunguses 

8,100 

Tursus 

12,100 

Tardus 

200 

Tuscany 

4,200 

Tugaloo 

8,200 

Tutsan 

12,200 

Tardation 

300 

Tuck alio es 

4,300 

Tygarts 

8,300 

Tussah.s 

12,300 

Tardacious 

400 

Tui’tle 

4,400 

Tuggerah 

8,400 

Tusseiner 

12,400 

Tadde 

500 

Tumbles 

4,500 

Tuggers 

8,500 

Tussers 

12,500 

Tandems 

600 

Tucking 

4,600 

Turgid 

8,600 

Tussicular 

12,600 

Tardily 

700 

Tulips 

4,700 

Tui'gidness 

8,700 

Tursins 

12,700 

Tardiness 

800 

Turcoman 

4,800 

Tungo 

8,800 

Tussock 

12,800 

Tar do 

900 

Turcois 

4,900 

Turngourds 

8,900 

Tysonites 

12,900 

Tarldons 

1,000 

Tubule 

5,000 

TumiJlt 

9,000 

Tufty 

13,000 

Taffy 

1,100 

Tubulous 

5,100 

Tumulous 

9.100 

Tutuilas 

13,100 

Taffys 

1,200 

Tubal 

5,200 

Tumman 

9,200 

Tutary 

13,200 

Tafa 

1,300 

Tiu’bans 

5,300 

Turmalines 

9,300 

Turntables 

13,300 

Tafalla.s 

1,400 

Tube 

5,400 

Tumefy 

9,400 

Tutelary 

13,400 

Tafeta 

1,500 

Tuberous 

5,500 

Tumefies 

9,500 

Tutelages 

13,500 

Taflerels 

1,600 

Turbid 

5,600 

Tumid 

9,600 

Tutti 

13,600 

Tafi 

1,700 

Turbidness 

5,700 

Tumid.ne3s 

9,700 

Tuitions 

13,700 

Tafias 

1,800 

Tyboe 

5,800 

Tumor 

9,800 

Tutoring 

13,800 

Tarfork 

1,900 

Turbots 

5,900 

Turmoils 

9,900 

Tutors 

13,900 

Taifords 

2,000 

Turfdum 

6,000 

Tunny 

10,000 

Tally 

14,000 

Taguan 

2,100 

Turdulis 

6,100 

Turnus 

10,100 

Tallcs 

14,100 

Tagus 

2,200 

Tyndall 

6,200 

Timable 

10,200 

Tankard 

14.200 

Taganet 

2,300 

Tyndarus 

6,300 

Tunas 

10,300 

TaUages 

14,300 

Tagals 

2,400 

Tysdell 

6,400 

Turney 

10,400 

Tape 

14.400 

Tangent 

2,500 

Tydeus 

6,500 

Tunnels 

10,500 

Tales 

14,500 

Targets 

2,600 

Tundish 

6,600 

Tuning 

10,600 

Talking 

14,600 

Tangible 

2,700 

Tuditanus 

6,700 

Turnips 

10,700 

Tapis 

14,700 

Taggings 

2,800 

Tudor 

6,800 

Turnover 

10,800 

Talcose 

14.800 

Tagolanda 

2,900 

Tudorous 

6,900 

Turnouts 

10,900 

Talons 

14,900 

Tagouts 

3,000 

Turfy 

7,000 

Turung 

11,000 

Tabular 

15,000 

Talmud 

3,100 

Tyfus 

7,100 

Tyrus 

11,100 

Tabulates 



3,200 

Turf an 

7,200 

Tyrannical 

11,200 

Tabasco 



3,300 

Tuffas 

7,300 

Tyrants 

11,300 

Tabards 



3,400 

Turfed 

7,400 

Turret 

11,400 

Taber 



3,500 

Turfers 

7,500 

Tui’eens 

11,500 

Tabernacles 



3,600 

Tuficani 

7,600 

Tm-io 

1 1 ,600 

Tabid 



3,700 

Turfings 

7,700 

Tyrians 

11,700 

Tabidness 



3,800 

Tuffoon 

7,800 

T3rro 

11,800 

Taboo 



3,900 

Tyfoons 

7,900 

Tyrones 

11,900 

Taborets 



4,000 

Tuggy 

8,000 

Tucksy 

12,000 

Tardy 




CODE FOR AAIOUNT, KIND, AND DIRECTION OF CLOUDS. 


Direction moving from — 


Ono tenth or Iosb. 


Two or three tenthB, 


Four or five tenths. 


Six or seven tenths. 


Eight, nine, or ten 
tenths. 


CIRRUS OR (TRRO-STRATUS— CU. 


North 

Cubby 

Cuban 

Cubeb 

Cubic 

Cupboard. 

Curdog. 

Curfoot. 

Northeast 

Cutduck 

Cudahy 

Cudden 

Cudding 

East 

Cuffy 

Cufa 

Curfew 

Curfish 

Southeast 

CutguU 

Cuptrall 

Cudgel 

Curgill 

Cutgown. 

Cupmore. 

Cunot. 

South 

Cumulate 

Cushman 

Culmen 

Culminate 

South'west 

Cutnut 

Cunard 

Cunette 

Cunning 

West 

Curry 

Curate 

Currency 

Cupric 

Culrow. 

Northwest 

Curtsy 

Cupsail 

Curser 

Cursing 

Cursory. 







Cl R ROG-UM ULUS— C A . 


North 

Carbuncle 

Cabal 

Campbell 

Northeast 

Candy 

Cadaver 

Cadet 

East 

Canful 

Carfare 

Cafe 

Southeast 

Catgut 

Cargason 

Caere 

South 

Calmy 

Carman 

Camel. 

Southwest 

Canuck. 

Canal 

Canner 

West 

Carrying 

Caramel 

Careen 

Northwest 

Catsup 

Cassada 

Cause 






Carbine. 
Cardinal 
Catfish. . 
Caging. . 
Camille.. 
Canine.. 
Carrion.. 
Casing. . 


Carbon, 

Caddo. 

Canform, 

Cargo. 

Camon. 

Canoe. 

Carroll. 

Cassock. 


106 


INSTEUCTIONS FOR AEROLOGICAL OBSERVERS. 

CODE FOR AMOUNT, KIND, AND DIRECTION OF CLOUDS— Continued. 


1 

Direction moving from — One tenth or less. 

Two or thi’ee tenths. 

Four or five tenths. 

Six or seven tenths. 

Eight, nine, or ten 
tenths. 


ALTO-STRATUS- 

-CE. 




North. 


Cebu 

Cebal 

Cerbera 

Cerbit 

Cedule 

Cedar 

Cedent 

Cedive 

Ceffy 

Cefalu 

Ceffel 

CeUfish . . 

Ceggum 

Cellgage 

Ceggert 

Ceggick 

Cemmure 

Celtman 

Cement 

Cepmist 

Cernum 

Cenation 

Ceneda 

Cenity. . 

Centrule 

Central 

Ceremony 

Centrist 

Censure 

Cessant 

Cessement 

Cession 






Cellbox. 

Cedose. 

Celfoil. 

Cellgown. 

Cemoin. 

Cenotaph. 

Cedron. 

Censor. 


CUMULUS— Cl. 


North 

Northeast. 

East 

Southeast. 

South 

Southwest. 

West 

Northwest 


Cimbud Cimbal 

Ciddy 

Cinda 

Ciffum 

Cifax 

Ciggum 

Cigar 

Cirmul 

Cimar 

Cinura 

Cinnamon 

Cirrum 

Citrate 

Cissy 

Cissail 




Cibert. . 
Cider. . . 
Cilfem. . 
Cigent. . 
Cimeter 
Cisney. . 
Cipreal.. 
Ciselure 


Cimbia 

Cilbom. 

Cidick 

Cindow. 

Cinfix 

Cinfoot. 

Ciggish 

Cingold. 

Cimid 

Cimone. 

Cimnit 

Cilnot. 

Citrine 

Citron. 

Cissing 

Cirsome. 


STRATO-CUMULUS— CO. 


North 

Northeast. 

East 

Southeast. 

South 

Southwest, 

West 

Northwest 


Combustion 

Conduct. 

Confuse 

Cowgut 

Commute. . . 
Connubial. . . 

Corrupt 

Consult 


Combat... 
Cordage. ., 

Confab 

Coalgate. 
Command 
Coinage... 
Contract. . 
Corsage... 


Combed 

Code 

Confer 

Congeal 

Comedy 

Cockney 

Congregate 
Consent. 


Coalbin . . . 
Codding. . . 
Confide. . . 
Cogging... 
Coming. . . 
Cognizant 
Contrite. . 
Consist 


Coalbox. 

Condole. 

Comfort. 

Congo. 

Common. 

Cognomen. 

Control. 

Consort. 


STRATUS— Cn. 


North 

Northeast. 

East 

Southeast. 

South 

Southwest, 

West 

Northwest 


Chubby. . . . 
Churchdue 

Chaffy 

Chagull 

Chummy. . 
Chestnut. . 
Cherub . . . . 
Choisy 


Chainball. 

Chadam.. 

Chufa 

Chigga.... 

Chapman. 

China 

Charade. . 
Chainsaw 


Chamber, 

Chide 

Chafer. . . 
Change. . 
Charmed 
Channel. 
Children. 
Chisel 


Childbirth 

Chendi 

Chaffing... 
Chugging. 
Chemical. 
Churning . 
Chagrin... 
Chasing. . . 


Checkbook. 

Chaldon. 

Chaff o. 

Chagon. 

Chamon. 

Chignon. 

Chapron. 

Chanson. 


NIMBUS OR CUMULO-NIMBUS— CL OR CR. 


North 

Northeast. 

East 

Southeast. 

South 

Southwest, 

West 

Northwest 


Cloudburst 

Cloddy 

Cleffy 

Clergy 

Clammy. . . 
Cranny. . . . 

Cleary 

Clumsy 


Cribbage. 
Classday. . 
Clockface. 
Clubgate.. 
Climate. . . 
Clampnail 

Clara 

Crusade... 


Clubbed.. 

Crude 

Crowfeet, 
Cringe . . . 
Claimer.. 
Cleaner.. 
Claret. . . 
Crossed.. 


Climbing 
Credit. . . 
Clopfish.. 
Clogging 
Criminal. 
Clannish . 
Clarify. . . 
Classify. . 


Crossbow. 

Cladonia. 

Clubfoot. 

Clackgoose. 

Clamor. 

Crinoline. 

Clubroom. 

Crimson. 


INSTIUJCTIONS FOR AEROLOGICAL OBSERVERS. 


J07 


CODE FOR VISIBILITY. 


Descriptive term. 

Limiting 

distance. 

Code words. 

Dense fog — prominent objects not visi- 
ble at 

Meters. 

50 

Zero. 

Very bad — prominent objects not visi- 



ble at 

200 

One. 

Bad — prominent objects not visible at.. 

500 

Two. 

Very poor— prominent objects not 



visible at 

1,000 

Three. 

Poor — prominent objects not visible at. 

2,000 

Four. 

Indifferent — prominent objects not 



visible at 

4,000 

Five. 

Fair — prominent objects not visible at. 

7,000 

Six. 

Good — prominent objects not visible 



at 

12,000 

Seven. 

Very good — prominent objects not 



visible at 

30,000 

Eight. 

Excellent — prominent objects visible 

beyond 

30,000 

Nine. 


8. FORMS AND REDUCTION TABLES. 

The Forms to be used in pilot-balloon work are 1110- 
Aer., 1111-Aer., 1112-Aer., 1113-Aer., 1114-Aer., 1115- 
Aer., and 1116-Aer. 

Form No. 1110-Aer., Table 19, is for the recordmg of 
all data in any way connected with the observation. 
The beading must be carefully made out and the remain- 
ing spaces filled in so far as possible. The observation 
point, altitude (of observing point), and zero setting, 
whether on north or south, will be given on each Form. 
The names of the observer and the recorder should not 
be omitted. Particular attention is to be given to the 
recording of the disappearance of the balloon. When it 
is due to clouds, it will be stated distinctly whether 
against, into, or behind them. The balloon data and the 
meteorological data will be entered in complete form in 
each case. The wind direction and velocity at the sur- 
face will be recorded to the nearest one of the 16 compass 
points and in meters per second. The temperatui’e (both 
dry and wet bulb readings) is to be recorded in degrees 
and tenths centigrade. For the conversion of Fahren- 
heit temperatures, see Table 29. Both station and sea- 
level pressure will be entered in millibars. See Table 31. 
Base line, length, and azimuth will be recorded only in 
double-theodolite work. Visibility and sun will be re- 
corded according to scale as set forth near tlie end of 
section 4. Form No. 1110-Aer. will bo rendered only 
when an ascension is made. In the event that one or 
more observations result in no ascension, this informa- 
tion will be entered on the succeeding Form in the space 
for notes, under the heading 

No ascenfiion for, 
a. m. Date p. m. 

If the space is insufficient, refer to the back of sheet 
and enter the data there, referring thereto by entry in 
notes. 

Form No. 1111-Aor., Table 24, is for station use and 
is designed for the convenience of the Official in Charge. 


Rendition of this Form will depend upon the need for such 
data, at the discretion of the Official in Charrro. 

Form No. 1112-Aer., Table 23, is a summary of the 
week’s work, from the a. m. observation of Sunday to 
the p. m. observation of Saturday, inclusive. An entry 
on this Form must be made for each scheduled observa- 
tion during that period — that is, an entry must be made 
for the a. m. and p. m. observation during the week. A 
single line must be left blank between each entry. When 
an ascension is made, the entry will consist of the data 
taken from Form No. 1110-Aer. Note that entry for the 
tenth a. m. agrees with the data on Form No. 1110-Aer., 
Table 19. In the event of no ascension, due to low 
clouds, etc., the entry for the observation will state the 
reason why. See entry for the seventh a. m.. Table 23. 
No ascension was made at that time, due to low clouds. 
Entries will also be made for special observations. 

Form No. 1113-Aer., Table 25, is for the reporting of 
knowm cloud altitudes for the month. Much care should 
be taken in selecting data for this Form. Questionable 
data should not be recorded, or, if recorded, should be 
so indicated in space under “remarks.” 

Form No. 1114-Aer., Table 22, is a monthly summary 
for all observations for specified levels. One Form is 
used for summarizing a. m. observations, and a second is 
used for summarizing the p. m. observations. Care must 
be taken that data for an a. m. observation are not re- 
corded on the p. m. Form. For a regular ascension these 
data will be taken from Form No. 1115-Aer. Note that 
data in the space for a. m. of the 10th agree with those 
on Form No. 1115-Aer., figure 49, for the single-theodo- 
lite graph. WTien the observation results in no ascen- 
sion, the reason will be entered in the corresponding 
space on this Form; thus, no observation on the a. m. 
of the 7th, due to low clouds, is recorded on the a. m. 
sheet and in the space for that date. When the ascen- 
sion extends over 10,000 meters in altitude, the data for 
each kilometer abov^e that level will be entered on the 
reverse side of the sheet. In this event it will be signi- 
fied in the corresponding space under “remarks.” 

Form No. 1115-Aer., figure 49, is a graphical repre- 
sentation of the data obtained from the ascension. The 
construction of the graphs themselves has alread}'^ been 
explained in section 6. The lieading should agree in all 
details with Form No. 1110-Aer., Table 19. Special 
attention will bo given to date, time, and ascension num- 
ber. The meteorological data in the upper left-hand 
corner of the Form should agree with those on the Form 
No. 1110-Aer. Form No. 1115-Acr. will be rendered 
only when an ascension is made. When the observation 
results in no ascension, the reason for the same will bo 
entered in the upper right-hand corner of the succeeding 
Form under 

No ascension for, 
a. m. Date p. in. 

Form No. 1116-Aer., Table 21, is for the station file, 
and is designed to assist the observer in accurately coding 


108 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 


the telegraphic report. The data for the specified levels 
arc derived from Form No. 1115-Aer., and entered on 
first blank line of Form No. 1116-Aer. The coded infor- 
mation is then entered on the second blank line. This 
Form will he rendered for each observation that is tele- 
graphed. When the regular telegraphic observation re- 
sults in no ascension, due to low clouds, etc., this infor- 
mation will replace the regular data and be entered in 
the space under “state of the weather.” 

From the above we see that an observation resulting 
in no ascension, due to low cloud, rain, snow, etc., is 
noted on each of the required Forms, or the reason for no 
ascension will be entered upon Forms Nos. 1110-Aer., 
1112-Aer., 1114-Aer., 1115-Aer., and 1116-Aer. in each 
case. All Forms will be rendered promptly and with a 
view to accuracy and legibility. 

Table 26, “Rate of Ascent in Meters per Minute,” is 
for the determination of ascensional rates of balloons in- 
flated by “indefinite method,” explained in section 3. 
The argument “free lift” (1), ranging from 55 grams to 
650 grams at intervals of 5 grams, will be found in the 
vertical column at the extreme left of the table; the 
weight of the balloon (w), ranging from 10 grams to 90 
grams at intervals of 2 grams, along the first horizontal 
line heading each column. Table 26a, supplementary to 
Table 26, gives ascensional rates for values of w and I 
most commonly in use, viz., 16 to 40 and 75 to 250 grams, 
respectively, both and I being given at intervals of 1 
gram. Thus no interpolation is necessary. 

Table 27, “Altitude Time Tables for Various Rates of 
Ascent,” gives the altitude of the balloon at any minute 
from 1 to 40 for ascensional rates of each 10 meters from 
150 meters per minute to 270 meters per minute, inclusive. 
This table has its specific application for balloons inflated 
by indefinite inflation. Each column contains multiples 


of the ascensional rate and minute of time in succession. 
Note the additive correction for the first five minutes. 

Table 28, “Free Lift for Definite Inflation,” gives the 
amount of free lift required to attain a definite ascen- 
sional rate of 140, 160, 180, 200, 220, 240, and 260 meters 
per minute for any weight of balloon from 15 to . 60 
grams, inclusive. 

Table 29 aids in the conversion of Fahrenheit tempera- 
tures in degrees and tenths to centigrade degrees and 
tenths. The range of the table in Fahrenheit tempera- 
ture is from —36° to 100° by tenths of degrees. Note 
that each column of centigrade temperatures is arranged 
with two columns of Fahrenheit temperatures, one on 
either side. The values in the centigrade column when 
associated with the Fahrenheit column on the left are as 
they appear in print, but when associated with the Fah- 
renheit column on the right the value is reversed. That 
is, 5°.0 C. when associated with 41° F. is above zero, but, 
when associated with 23° F., is below zero. The tenths of 
Fahrenheit degrees are converted by noting the ending 
of the centigrade temperature for the whole Fahrenheit 
degree, finding this in the column headed “P. P.,” and 
moving down the scale the number of spaces equivalent 
to the number of tenths of degrees to be converted. For 
instance, a temperature of 58°. 8 F. is equivalent to 14°. 9 
C. Opposite the whole degree 58 and in the C. column 
is found 14°.44. The ending .44 is found in column 
“P. P.” Since the tenths of a degree to be converted 
are 8, we move down the column 8 spaces and there find 
.89; this when substituted for the ending .44 of the C. 
value 14.44 gives us the temperature 14.89, or 14°. 9 C. 
Likewise any Fahrenheit temperature within the limits 
stated can he converted to degrees and tenths of the 
centigrade scale. 

Tables 30 and 31 are self-explanatory. 


INSTRUCTIONS FOR AKROI.OOICAL OHSKRVURS 


109 


Tablk 20 . — Hale of ascent, in meters per minute, for given weight {w) and free lift (1). 


w. 


1. 

10 

12 

14 

16 

18 

20 

22 

24 

2fi 

28 

30 

.32 

34 

:ifi 

38 

40 

42 

44 

46 

48 

.‘>0 

1.50. 8 

148,7 

146.8 

144.9 

143. 1 

141.4 

139.7 

138.1 

136.6 

13.5.2 

13,3.8 

1.32. 3 

1.31.0 

129. 8 

128.5 

127.4 

126. 2 

m.i) 

12-1 0 

122,0 


1.54,8 

1.52. 8 

i:>i.o 

149.2 

147.5 

145. 8 

144.2 

142.7 

141.2 

139,8 

138.4 

l;37. 1 

135. 8 

1.34,5 

i:i3.3 

i:i2. 1 

131 . 0 

129.9 

128.8 

127.8 

()0 

1.58. 1 

I5(i. 0 

1.54.8 

1.53. 1 

151.5 

149. 9 

148.3 

146. 9 

145. 4 

144.0 

142.7 

141.4 

140.1 

1.38.9 

137.7 

1.36. 6 

1.3.5. 4 

134.4 

133.3 

i:i2.3 

1)0 

101.9 

160. 1 

158. 4 

1.56. 8 

155.2 

1.53.6 

1.52. 1 

1.50. 7 

149.3 

148.0 

146.7 

145. 4 

144. 2 

143. 0 

141.8 

140.7 

1 39. 6 

138.5 

137.5 

136.4 

70 

16.5, 0 

163.3 

161.7 

160. 1 

1.5S. 6 

1.57. 1 

155. 7 

1.54.3 

1.52. 9 

151.6 

150.4 

149.1 

147.9 

146. 8 

145. 6 

144. 5 

14.3.4 

142.4 

111.4 

140.4 

7.-, 

16S.0 

166.4 

164.8 

16,3.3 

161.8 

UX).4 

159. 0 

1.57. 7 

1.56. 4 

1.55. 1 

1.53. 8 

152. 6 

151.5 

150. 3 

149.2 

148. 1 

147.1 

146. 0 

145. 0 

144.0 

SO 

170.8 

169. 2 

167.7 

l(Xi.3 

164. 9 

163.5 

162. 1 

160. 8 

1.59.5 

158.3 

157. 1 

1.5.5. 9 

1.54. 8 

153.6 

152. 6 

1.11.5 

1.50. 5 

149, 5 

148.5 

147.5 

8.> 

173.4 

171.9 

170. 5 

169. 1 

167. 7 

166.4 

16.5. 1 

163. 8 

162. 6 

161.3 

160. 2 

1.59. n 

1.57. 9 

156. 9 

155,8 

1.54.7 

153. 7 

152. 7 

151.7 

1.50. 8 

90 

176.0 

174.5 

173.1 

171.7 

170.4 

169.1 

167. 8 

166.6 

16,5. 4 

164.2 

163. 1 

162. 0 

160. 9 

159. 8 

158. 8 

157.7 

156, 7 

1.5.5 8 

1.54. 8 

1.53.9 

9.'> 

178.3 

176.9 

175. 6 

174.3 

173.0 

171.7 

170.5 

169. 2 

168.1 

167. 0 

16.5, 8 

164.8 

163.7 

162. 6 

161.0 

160.6 

159. 6 

158. 7 

1.57.7 

156. 8 

100 

180.6 

179.3 

177.9 

176.7 

175. 4 

174.2 

173.0 

171.8 

170.7 

169. 6 

168.5 

167.4 

166, 4 

165. .3 

164.3 

163.3 

162.4 

161.4 

nil). 5 

159.6 

lO.I 

182.8 

181.5 

180.2 

179,0 

177.7 

176.5 

175. 4 

174.2 

173.1 

172.0 

171,0 

169. 9 

168. 9 

167.9 

166. 9 

166.0 

Hi.5. 0 

164.1 

16.3. 2 

162.3 

no 

181.9 

183.6 

182.4 

181.1 

180.0 

178.8 

177.7 

176.6 

175.5 

174.4 

173.4 

172.3 

171.3 

170.4 

169. 4 

168. 5 

167.5 

166. 6 

16.5. 7 

164. 8 

115 

186.9 

185.6 

184.4 

183.2 

182.1 

181.0 

179.9 

178.8 

177.7 

176.7 

175. 7 

174.7 

173 7 

172.7 

171.8 

170.9 

160.9 

169.0 

168.2 

167. 3 

120 

188.8 

1.S7.6 

186.4 

185.3 

184.2 

1,83.1 

182.0 

180.9 

179.9 

178.9 

177.9 

176.9 

175. 9 

175.0 

174.1 

173.2 

172.3 

171.4 

170.5 

169. 7 

12.5 

190,7 

189.5 

188.4 

187.3 

186.2 

18). 1 

184.0 

183.0 

182.0 

181.0 

180.0 

179.1 

178.2 

177.3 

176, 1 

175.4 

174.5 

173. 6 

172.8 

171.9 

130 

192.4 

191.3 

190.2 

189.1 

188.0 

187.0 

186.0 

185.0 

184.0 

183.0 

182.0 

181.1 

180.2 

179.3 

178.4 

177. 5 

176.6 

175. 8 

174.9 

174. 1 

135 

194.2 

193.1 

192.0 

191.0 

1.89.9 

188.9 

187.9 

18f).9 

185.9 

185.0 

184.1 

183.2 

182.2 

181.3 

l.SO. 4 

179. 6 

178.7 

177.9 

177.0 

176, 2 

140 

19.5. 9 

194.8 

193. 7 

192.7 

191.7 

190.7 

189.7 

188.7 

187.8 

186.8 

185.9 

185.0 

181. 1 

183.2 

182.4 

181.5 

180.7 

179.9 

179.1 

178.3 

145 

197.5 

196.4 

195. 4 

194.4 

193. 4 

192. 4 

191.5 

190.6 

189.5 

188.6 

187.8 

186.9 

186.0 

1.S5.2 

184.3 

183.5 

182.6 

181. S 

181.0 

180.2 

loO 


198.0 

197.0 

196.0 

195. 1 

194.1 

193.2 

192.2 

191.8 

190.4 

189.5 

188.6 

187.8 

187,0 

186. 1 

18.5.3 

184.5 

183.7 

1S2.9 

182.2 



199.6 

198.6 

197.6 

196.7 

195. 7 

194.8 

193.9 

193.0 

192. 1 

191.3 

190. 4 

189.6 

188.7 

187.9 

187.1 

18t>.3 

185.5 

18-1. S 

184. 0 

100 


201. 1 

21X1.2 

199.2 

198.3 

197.3 

196. 4 

195.0 

194.7 

193.8 

193.0 

192.1 

191.3 

190.5 

189.7 

188,9 

188.1 

187.3 

186.5 

18.5.8 



202. 0 

201 . 6 

200.7 

199.8 

198.9 

198.0 

197.1 

196.3 

195.4 

194.6 

193.7 

192.9 

192.1 

191.3 

190. 6 

189,8 

1S9.0 

188.3 

187.5 

170 


204.0 

203.1 

202.2 

201.3 

2(X).4 

199.5 

198.7 

197.8 

197.0 

196.2 

195.3 

194.5 

193.8 

193.0 

192.2 

191.4 

190.7 

190. 0 

189.2 

17o 



204.5 

103.6 

202.7 

201.9 

201.0 

200.2 

199. 3 

198.5 

197.7 

196. 9 

106. 1 

195.3 

194.6 

193. 8 

193.1 

192. 3 

191.6 

190.9 

ISO 



205. 9 

205, 0 

204.1 

203,3 

202.4 

201.6 

200.8 

200. 0 

199.2 

198. 1 

197.6 

196.8 

196. 1 

195.4 

194. 6 

193.9 

193. 2 

192. 5 

185 



207.2 

206.4 

205. 6 

204. 7 

203.9 

203. 0 

202.2 

201.4 

200 7 

199.9 

199.1 

198.4 

197. 6 

196. 9 

196. 2 

195.5 

194. 7 

194.0 

190 



208, () 

207.7 

2(Xi. 9 

2 tm.o 

205.2 

204.4 

203.6 

202.9 

2f)2. 1 

201.3 

2(K). fi 

199. 8 

199.1 

198. 4 

197.7 

197.0 

196. 3 

195. 6 

195 



209.8 

209.0 

208.2 

207.4 

206. (i 

20.5.8 

2a5.0 

201.2 

203.5 

202.7 

202. 0 

201.3 

200.6 

199.9 

199. 1 

198.4 

197.7 

197.1 

200 




210.3 

209,5 

208.7 

207.9 

207.1 

206. 3 

20.5.6 

204.8 

20.1.1 

203.4 

202. 7 

201.9 

201.2 

200. 5 

199.9 

199.2 

198.5 

205 




211.4 

210.6 

209.9 

209.2 

208.4 

207.6 

206.9 

20fi. 2 

20.5.4 

20*1. 6 

204.0 

203.3 

202.6 

201.9 

201.3 

200. 6 

199.9 

210 




212. 8 

212.0 

211.2 

210. 4 

2t>9.7 

208.9 

208. 2 

207. 5 

2«'6.8 

206. 0 

20-5.3 

204.7 

204.0 

203. 3 

202.6 

202.0 

2(il.3 

215 




214.0 

213.2 

212.4 

211.6 

210.9 

210.2 

209.5 

208.7 

208.0 

207.3 

206. 7 

20(1. 0 

205. 3 

204. 6 

204.0 

203. 3 

202. 7 

220 




215. 1 

214,4 

213.6 

212.9 

212.2 

211.4 

210.7 

210.0 

209.3 

208.6 

207.9 

207. 3 

206. 6 

205. 9 

205. 3 

204.6 

204.0 

225 





215.5 

214.8 

214.1 

213.4 

212.7 

212.0 

211.2 

210.5 

209.9 

209.2 

208. 5 

207. 9 

207,2 

206. 6 

205. 9 

205.3 

230 





216. 6 

215. 9 

215.2 

214.5 

213.8 

213. 1 

212.4 

211.7 

211.1 

210. 4 

209.7 

209.1 

208. 4 

207.8 

207.2 

206. 6 

235 





217.7 

217.0 

216. 3 

215.7 

215.0 

214.3 

213.6 

212. 9 

212.2 

211.6 

210.9 

210. 3 

209. 7 

209.0 

20a4 

207.8 

240 





218.8 

218.1 

217.4 

216-7 

216. 1 

215.4 

214.7 

214. 1 

213.4 

212.8 

212. 1 

211.5 

210. 9 

210. 3 

209. 6 

209. 0 

245 





220.0 

219.2 

218.5 

217.8 

217.2 

216. 5 

215. 9 

215.2 

214.6 

213.9 

213. 3 

212.7 

212.0 

211.4 

210. 8 

210.2 


w. 


50 

52 

54 

56 

58 

60 

62 > 

64 

00 

68 

70 

72 

74 

76 

78 

SO 

82 

84 

86 

,88 

50 

121.9 

120 9 

119.9 

118.9 

118.0 

117. 1 

116.2 

115.4 

114. () 

11.3.7 

1 12. 9 

1 12. 2 

III. 4 

110. 7 

109. 9 

109. 2 





55 

126. 7 

12.5 7 

124.8 

123.8 

122.9 

122. 0 

121. 1 

120.3 

1 19. 5 

Ilh. 6 

117.9 

117. 1 

U().3 

1 15. 6 

114.8 

114. 1 





(SO 

131.2 

130. 3 

129.3 

128.4 

127.5 

126. 6 

1'2.5. 7 

124.9 

124. 0 

12:1.2 

122. 4 

121.6 

120.9 

120. 1 

1 19. 4 

118.7 





05 

135. 4 

134.5 

133. 5 

132. 6 

131.7 

130. 8 

130. 0 

129. 1 

128. 3 

127.5 

:'20. 7 

125. 9 

125. 2 

124. 1 

12:i. 7 

123. 0 





70 

139. 4 

138. 4 

137.5 

136. 0 

1.3.5. 7 

134.8 

134. 0 

133. 1 

132. 3 

131.0 

i:iO. 7 

129.9 

129.2 

12,8. 4 

127. 7 

127.0 





75 

143.1 

142. 1 

141.2 

140.3 

139.4 

138.6 

137.7 

136.9 

1.36. 1 

13.5. 3 

1.34. 5 

i;i3. 7 

133.0 

132,2 

131. 5 

130. 8 

130. 1 




80 

146.5 

145.6 

144.7 

143. 8 

142.9 

142. 1 

111.2 

140.4 

139. 6 

138. 8 

1;J8. 0 

137. 3 

136.6 


135. 1 

134. 4 

i:i3. 7 




85.. 

149.8 

148.9 

148.0 

147. 1 

146. 3 

145. 4 

144.6 

143. 8 

143.0 

142.2 

Ui. 4 

140.7 

139.9 

139.2 

138. 5 

137.8 

137. 1 




90 

152. 9 

1,52.0 

1.51.2 

1.50.3 

149. 4 

148.6 

147. 8 

147.0 

146.2 

14.5. 4 

144.7 

143.9 

143.2 

1 12. 5 

141.7 

141.0 

140.4 




95.. 

155.9 

155.0 

154. 1 

153. 3 

152. 4 

151. 6 

1.50. 8 

150. 0 

149. 2 

148. 5 

147.7 

1 17. 0 

146.3 

1 15. 5 

144. 8 

114. 1 

143. 5 




100 

158.7 

157. 8 

1.57. 0 

1,56. 1 

1.55. 3 

1.54. 5 

153.7 

152.9 

152.2 

151.4 

150. 7 

149.9 

149.2 

148. 5 

117.8 

147.1 

116.4 

145.8 



105 

161.4 

100.6 

1.59. 7 

158. 9 

1.58. 1 

157. 3 

1.56. 5 

155.7 

1.54. 9 

1.54. 2 

1.53. 4 

152. 7 

1.52. 0 

151.3 

1.50. 6 

149. 9 

149.3 

148. 6 



110. 

104.0 

163. 1 

162.3 

161.5 

160.7 

159. 9 

1 59. 1 

158. 4 

157. 6 

l.VS. 9 

1 .56. 1 

155. 1 

154. 7 

151. 0 

1 53. 3 

152. 7 

152. 0 

151. 3 



115.. . 

\m. 5 

165. 6 

1(S4. 8 

164. 0 

163. 2 

162. 4 

161.7 

160.9 

160. 2 

159.4 

158. 7 

I5H.0 

157. 3 

156. 6 

15',. 9 

l.VS. 3 

154. 6 

1 54. 0 



120. 

108. 8 

168. 0 

167. 2 

l()6. 4 

165. 6 

HU 9 

164. 1 

163. 4 

162. 6 

161.9 

Hil. 2 

100. 5 

!;59. 8 

159 1 

l.Vs. 4 

157. 8 

157. 1 

156. 5 



125 

171. 1 

170.3 

109.5 

168.7 

168. 0 

107.2 

166. 5 

10;5. 7 

165. 0 

164.3 

163. 6 

162. 9 

162.2 

161.5 

1110.9 

160.2 

159. 6 

1.58. 9 

1,58, 3 


130 

173.3 

172.5 

171.7 

171.0 

170. 2 

169. 5 

16K. 7 

168.0 

167. 3 

mi 6 

16.5.9 

165. 2 

164. 5 

163. 8 

163. 2 

162. 5 

161.9 

161.3 

160. 6 


135 

17.5.4 

174.7 

173.9 

173. 1 

172. 4 

171.6 

170.9 

170. 2 

169. 5 

168.8 

168. 1 

167. 4 

166. 7 

166. 1 

16.5. 4 

164. 8 

161. 2 

163. 5 

162. 9 


140 

177. 5 

170.7 

176.0 

175.2 

174.5 

173. 7 

173.0 

172.3 

171.6 

170.9 

170.2 

169.6 

I6H.9 

168. 3 

167. 6 

167. 0 

161). 3 

165. 7 

16,5. 1 


145 

179. 5 

178.7 

178.0 

177. 2 

176.5 

175. 8 

175. 1 

174. 4 

173. 7 

173.0 

172.3 

171. 7 

171.0 

170. 1 

169. 7 

169. 1 

168. 5 

l()7. 9 



1.50 

181. 4 

180.6 

179.9 

179.2 

178.6 

177.7 

177. 0 

170. 4 

175.7 

17,5. 0 

174.3 

173.7 

17:1.0 

172. 4 

171.8 

171. 1 

170. 5 

109. 9 

169. 3 

168.7 

1.55 

183.3 

182. 5 

181.8 

181. 1 

180.4 

179.0 

179.0 

178.3 

177.0 

176.9 

176. 3 

17.5. 6 

175. 0 

171. 4 

17:1.7 

173. 1 

172. 5 

171.9 

171.3 

170.7 

160 

185. 1 

184.3 

183. 0 

182.9 

182.2 

181.5 

IKO. H 

ISO. 2 

179.5 

178.8 

178.2 

177. 5 

176. 9 

176. 3 

17.5.7 

175. 0 

174.4 

173. 8 

173. 2 

172. 7 

165 

186.8 

186. 1 

18.5. 4 

184.7 

184.0 

183.3 

182.fi 

182. 0 

181.3 

180.7 

ISO. 0 

179. 4 

178.8 

178. 1 

177.5 

176.9 

176. 3 

175.7 

17.5.2 

171.6 

170 

188.5 

187.8 

187.1 

186.4 

185. 7 

18.5. 1 

184.4 

1.8.1. 7 

183. 1 

182.4 

181. 8 

181. 2 

180.6 

179.9 

179.3 

178.7 

178.2 

177.6 

177.0 

176.4 

175. 

190. 2 

189. 5 

18K. 8 

188. 1 

187. 4 

IMli 8 

186. 1 

185. .5 

184. K 

IS4 2 

\Ki. 5 

182. 9 

182. 3 

181. 7 

181. 1 

1 SO. 5 

179. 9 

179, 3 

178. S 

178.2 

IHO 

191.8 

191. 1 

190.4 

189.7 

189. 1 

188. 1 

187.8 

187. 1 

1H6. 5 

185.9 

185.2 

lK-1. 6 

IH4. 0 

iKl 4 

182.8 

182.2 

181.7 

181. 1 

180.5 

180. 0 

185 

193. 4 

192.7 

192. 0 

191.3 

190.7 

190. 0 

189. 4 

188, 8 

188. 1 

187.5 

186.9 

186.3 

185, 7 

185. 1 


183.9 

ih:i. 1 

182. 8 

182.2 

181.6 

190 

194.9 

194.2 

193. 6 

192.9 

192. 2 

191.6 

191.0 

190. 4 

189.7 

189. 1 

188. 5 

187. 9 

187. 3 

186. 7 

186. 1 

18,5. 6 

185. 0 

184. 4 

183.9 

183.3 

195. 

190.4 

195. 7 

195. 1 

194 4 

193 8 

193 1 

192 5 

lUI 9 

191. 3 

190 7 

190 1 

ISO Ti 

188 9 

188. 3 

187. 7 

187. 2 

186. 6 

186.0 

185. 5 

184. 9 

2(K) 

197.8 

197.2 

196.5 

195. 9 

195. 3 

191.6 

194. 0 

193. 4 

192. 8 

192. 2 

191.6 

191. 0 

190. 4 

1H9. 9 

189. 3 

188.7 

188.2 

187. 6 

187. 1 

ISO. 5 

205. . . 

199.3 

198. 6 

198. 0 

197 4 

196 7 

196 1 

195 .5 

194 9 

194 3 

193 7 

193 1 

19 2 r* 

191 9 

191 4 

190. S 

190. 2 

189. 7 

189. 2 

188, 6 

188. 1 

210 

200. 7 

200. 0 

199.4 

198. 8 

198.2 

197. 5 

196. 9 

196.3 

195. 7 

195. 2 

194.6 

194. 0 

193. 4 

192.9 

192. 3 

191. 7 

191. 2 

190. 6 

190. 1 

189. 6 

215 

202. 0 

201. 4 

200. 8 

200. 2 

199 h 

I9K 9 

19K 3 

197 7 

197 2 

196 6 

19<; 0 

19.5 4 

Hit 9 

194 3 

193. 8 

193. 2 

192. 7 

192. 1 

191. 6 

191. 1 

220 

203. 4 

202. 7 

202. 1 

201.5 

200.9 

200. 3 

199. 7 

199. 1 

198. 5 

198. 0 

197. 4 

196. 8 

196. 3 

195. 7 

195. 2 

194.6 

194. 1 

193.6 

193. 0 

192. 5 

225 

204. 7 

204. 1 

20;i. 4 

202 K 

202. 2 

201 6 

201 1 

‘AMI .'S 

199 9 

HKi 3 

198 8 

198 ‘2 

197 7 

197 1 

196. 6 

196 0 

195. 5 

195 0 

194. 4 

193. 9 

2:10 

205. 9 

205. 3 

204.7 

204. 1 

203. 0 

201.0 

202, 4 

201. 8 

'.!01.2 

200. 7 

200. 1 

199. 6 

199. 0 

198. 5 

197. 9 

!97. 4 

196.9 

196.3 

195. 8 

195. 3 

235 

21 '7. 2 

206. 6 

206.0 

20.5 4 

201 8 

204 2 

203 7 

‘AW 1 

'Hr}. 

•hV} 0 

•>01 4 

‘AU» 9 

*AM» A 


H8) :< 

UJ8 7 

198. 2 

197. 7 

197. 2 

196. 7 

240 

2iiS. 4 

207.8 

207. 2 

206.7 

206. I 

205. 5 

204. 9 

204. 4 

20^1. 8 

203. 3 

2(72 7 

202. 2 

201. IS 

201. 1 

2(M). 6 

200. 1 

199. 5 

199. 0 

198. 5 

198. 0 

245 

209. 6 

209.0 

208.5 

207.9 

207.3 

200.8 

2Ui.2 

205.6 

20.5. 1 

204.5 

204. 0 

203. 4 

202. 9 

202. 4 

201.9 

201. 3 

200.8 

200.3 

199. 8 

199. 3 


110 


INSTliUCTIONS FOR AEROLOGICAL OBSERVERS. 

Table 26. — Rate of ascent, in meters per minute, for given weight (w) and free lift (1) — Continued. 


w. 


1 . 



20 

22 

24 

26 

28 

30 

32 

34 

36 

38 

40 

42 

44 

46 

48 

50 

52 

54 

56 

58 

250, 

220.3 

210. G 

218.9 

218.2 

217.6 

217.0 

216.3 

215.7 

215.1 

214.5 

213.8 

213.2 

212.6 

212.0 

211.4 

210.8 

210.2 

209.7 

209.1 

208.5 

255 

221.3 

220.7 

220.0 

219.3 

218.7 

218.1 

217. 4 

216.8 

216.2 

215.6 

214.9 

214.3 

213.7 

213.1 

212.6 

212.0 

211.4 

210.8 

210.3 

209.7 

260 

222. 4 

221.7 

221. 0 

220.4 

219.8 

219.1 

218.5 

217.9 

217.3 

216. 7 

216.0 

215. 4 

214.9 

214.3 

213.7 

213.1 

212.5 

212.0 

211.4 

210.9 

26.', 

223.4 

222. 7 

222. 1 

221.4 

220.8 

220.2 

219. 6 

218.9 

218.3 

217.7 

217. 1 

216.6 

216.0 

215. 4 

214.8 

214.2 

213.7 

213.1 

212.6 

212.0 

270 

224.4 

223.7 

223.1 

222.4 

221. 8 

221. 2 

220. 6 

220.0 

219.4 

218.8 

218.2 

217.6 

217.0 

216.5 

215.9 

215.3 

214.8 

214. 2 

213.7 

213.1 

275 


224.7 

224. 1 

223.4 

222.8 

222.2 

221.6 

221.0 

220.4 

219.8 

219,3 

21 S .7 

218. 1 

217. 5 

217 0 

216. 4 

215.9 

215.3 

214.8 

214.2 



225.7 

225.0 

2‘>4.4 

223. 8 

223. 2 

222.6 

222.0 

221.4 

220.9 

220.3 

219 7 

219. 2 

218 6 

218 0 

217 5 

216 9 

216.4 

215. 9 

215.3 

285 


226.6 

226.0 

225.4 

224.8 

224.2 

223.6 

223.0 

222.4 

221.9 

221.3 

220 7 

220.2 

219 6 

219 1 

218. 5 

218 0 

217, 4 

216.9 

216.4 

2 Qn 


227. 6 

227.0 

226.4 

225. 8 

225.2 

224.6 

224.0 

223.4 

222. 9 

222. 3 

221.7 

221.2 

220.6 

220 1 

219 6 

219 0 

218. 5 

218.0 

217.4 

2 Q 5 


228.5 

227.9 

227.3 

226.7 

226.1 

225.5 

225.0 

224.4 

223.8 

223.3 

222,7 

222. 2 

221,6 

221. 1 

220. 6 

220.0 

219.5 

219.0 

218.5 

♦^00 



228. 8 

228.2 

227.6 

227. 1 

226.5 

225. 9 

225.4 

224.8 

224.3 

223 7 

223, 2 

222.6 

222 1 

221.6 

221.0 

220. 5 

220. 0 

219.5 




229.7 

229. 1 

228.6 

228.0 

227.4 

226.9 

226.3 

225. 8 

225.2 

224. 7 

224. 1 

223 6 

223 1 

222 5 

222 0 

221. 5 

221.0 

220. 5 

.*^10 



230.6 

230.0 

229.5 

228.9 

228.3 

227.8 

227.2 

220.7 

226. 2 

225.6 

225. 1 

224 6 

224. 0 

223 5 

223.0 

222.5 

222.0 

221.5 




231.5 

230.9 

230.4 

229.8 

229.3 

228.7 

228.2 

227.6 

227. 1 

226 6 

226.0 

225 5 

225 0 

224. 5 

224 0 

2‘23.4 

223.0 

222.4 

820 



232.4 

231.8 

231.2 

230.7 

230.1 

229.6 

229. 1 

228.5 

228.0 

227 .5 

226 9 

226 4 

•225 9 

225.4 

224 9 

224.4 

223.9 

223.4 

825 




232.6 

232.1 

231.6 

231.0 

230.5 

230.0 

229.4 

228.9 

228 4 

227.9 

227 4 

226 8 

226.3 

225. 8 

225.3 

224. 8 

224.3 

880 




233.5 

2.33.0 

232.4 

231.9 

231.4 

230.8 

230.3 

229.8 

229 3 

228 8 

228 2 

227 7 

227. 2 

226.7 

226. 3 

225.8 

225.3 

885 




234.4 

233.8 

233.3 

232.7 

232. 2 

231.7 

231.2 

230.7 

230 2 

229 6 

229 1 

228 6 

228 2 

227.7 

007 0 

226. 7 

226.2 

810 




235.2 

231.6 

234.1 

233.6 

233.1 

232.5 

232.0 

231. 5 

231 0 

230 5 

230 0 

229 .5 

229 0 

228.5 

228. 1 

227.6 

227. 1 

845 




236.0 

235.5 

234.9 

234.4 

233. 9 

233.4 

232. 9 

232 4 

231 9 

231 4 

230 9 

230 4 

229 9 

229 4 

229.0 

228.5 

22 S . 0 

8.50 





236.3 

235.8 

235.2 

234.7 

■234.2 

233.7 

233 2 

232 7 

232 2 

231 7 

231 3 

230 8 

230.3 

229.8 

229.4 

228.9 

8.55 





237.1 

236.6 

236.0 

235. 6 

235.0 

234. 6 

234 0 

233 6 

233.1 

23'> 6 

232 1 

231.6 

231.2 

230.7 

230. 2 

229.7 

860 





237.9 

237.4 

236.8 

236.4 

235. 9 

235. 4 

234 9 

234 4 

233.9 

233 4 

232 9 

232 5 

232.0 

231.5 

231.1 

230,6 

865 





238. 7 

238.2 

237.6 

237.2 

236.7 

236.2 

235. 7 

235. 2 

234 7 

234 2 

2.33 8 

233 3 

232. 8 

232. 4 

231.9 

231. 4 

870 





239.4 

238.9 

238. 4 

237.9 

237.4 

237.0 

2.86 .5 

236 0 

23.5. .5 

23.5 1 

234 6 

234. 1 

233.7 

233.2 

232.7 

232.3 

875 






239.7 

239.2 

238.7 

238.2 

237.8 

237 3 

236 8 

236 3 

235 9 

235. 4 

234.9 

231.5 

234.0 

233.6 

233. 1 

880 






240.5 

240.0 

239.5 

239.0 

238. 5 

238 1 

237 6 

237. 1 

236 6 

236 2 

235. 7 

235.3 

234.8 

234.4 

233.9 

885 






241.2 

240.7 

240.2 

239.8 

239.3 

238 8 

238 4 

237 9 

237 4 

237. 0 

236 5 

236. 1 

235.6 

235.2 

234.7 

390 






242.0 

2-41. 5 

241. 0 

240. 5 

240.1 

239.6 

239. 1 

238.7 

238.2 

237.8 

237.3 

236.9 

236.4 

236.0 

235.5 

805 






242.7 

242.2 

241.7 

241.3 

240. 8 

240 4 

239, 9 

239 4 

2-39 0 

238. 5 

238. 1 

237.6 

237.2 

236. 8 

236.3 

400 







2-12.9 

242.5 

242.0 

241.6 

241 1 

240 6 

240 2 

239. 7 

239 3 

238.8 

238. 4 

238.0 

237.5 

237. 1 

405 







243.7 

243.2 

212.7 

242.3 

241 8 

241 4 

2-10 9 

240 .5 

2-40 0 

239.6 

239,2 

23 S . 7 

238.3 

237. 9 

410 . . . 







244.4 

243.9 

243.5 

243.0 

242.6 

242. 1 

241.7 

241.2 

240.8 

240. 4 

239.9 

239.5 

239.0 

238.6 

415 







245.1 

244.6 

244.2 

243.7 

243.3 

242.8 

242. 4 

242.0 

241.5 

241. 1 

240.6 

240. 2 

239.8 

239.4 

420 







245.8 

245.3 

244.9 

244.4 

244.0 

243.6 

243. 1 

242.7 

242.2 

241.8 

241.4 

241.0 

240.5 

240. 1 









246.0 

245.6 

245.2 

244. 7 

244 3 

243 8 

243 4 

243 0 

24*2.6 

242. 1 

241.7 

241.3 

240.8 

430 








246.7 

246.3 

245.8 

245.4 

245.0 

244.5 

244 1 

243.7 

243.3 

242.8 

242.4 

242.0 

241.6 

435 








247.4 

247.0 

246.5 

246. 1 

245. 7 

245.2 

244.8 

244.4 

244.0 

243.6 

243.1 

242.7 

242.3 

440 








248. 1 

247.6 

247.2 

246 8 

246.4 

245.9 

245 5 

245. 1 

1 244.7 

244.2 

243.8 

243.4 

243.0 

445 








248. 8 

248.3 

247.9 

2-17.5 

247.0 

246.6 

246.2 

245.8 

245.4 

245.0 

244.5 

■244. 1 

243. 7 


w. 


i . 

60 

62 j 

64 

66 

68 

70 

72 

74 

76 

78 

80 

82 

84 

86 

88 

90 

250 

208.0 

207.4 

206.8 

206.3 

205.8 

205.2 

204. 7 

204.2 

203.6 

203.1 

■202. 6 

202.1 

201.6 

201.1 

200.6 

200. 1 

255 

209.1 

208.8 

208.1 

207.5 

207.0 

206.4 

205.9 

205.4 

■204. 9 

204.4 

203.9 

203.4 

202.8 

202.4 

201.9 

■201. 4 

260 

210.3 

209.8 

209.2 

208.7 

208.2 

207.6 

207. 1 

206.6 

206.1 

205.6 

205.1 

204.6 

204.1 

203.6 

203. 1 

202. 6 

265 

211.5 

210.9 

210.4 

209.9 

209.3 

208.8 

‘208. 3 

207.8 

207.3 

206.8 

206. 3 

20.5. 8 

20,5. 3 

204.8 

204.3 

203.8 

270 

212.6 

212.1 

211.5 

211.0 

210.5 

210.0 

209.5 

208. 9 

208.4 

207.9 

207.4 

207.0 

206.5 

206.0 

205.5 

■205. 0 

275 

213. 7 

213.2 

212.6 

212.1 

211.6 

211.1 

210.6 

210.1 

209. 6 

209. 1 

208.6 

208.1 

207.6 

207.2 

206. 7 

206. 2 

280 

214. 8 

214. 3 

213.8 

213.2 

212. 7 

212.2 

211.7 

211.2 

210.7 

210.2 

■209. 7 

209. 2 

■208. 8 

208.3 

207.8 

207. 4 

235 

215. 9 

215.3 

214.8 

214. 3 

213.8 

213.3 

212. 8 

212.3 

211.8 

211.3 

■210. 9 

210. 4 

■209. 9 

209. 4 

■209. 0 

208.5 

290 

216. 9 

216.4 

215.9 

215. 4 

21-1.9 

214.4 

213.9 

213. 4 

212.9 

2 r 2. 4 

212. 0 

211.5 

211.0 

210.5 

210.1 

209. 6 

295 

218.0 

217.4 

216.9 

216.4 

215.9 

215.4 

215.0 

214.5 

214.0 

213.5 

213.0 

212.6 

2 r 2. 1 

211.6 

■211.2 

210.7 

300 

219.0 

218.5 

218.0 

217.5 

217.0 

216. 5 

216.0 

215.5 

21,5. 0 

214.6 

214.1 

213.6 

213. 2 

212.7 

212.2 

211.8 

305 

220. 0 

219.5 

219.0 

218.5 

218.0 

217.5 

217.0 

218.6 

216.1 

215. 6 

21.5. 2 

214.7 

214. 2 

21 : 1 . 8 

213.3 

212.9 

310 

221.0 

220.5 

220.0 

219.5 

219.0 

218.5 

218.1 

217.6 

217.1 

216.6 

216.2 

215.7 

21,5. 3 

214.8 

214.4 

■213. 9 

315 

222. 0 

221.5 

221.0 

220. 5 

220.0 

219.5 

219. 1 

218.6 

218.1 

217. 7 

■217. 2 

216.7 

216.3 

215.8 

215.4 

21.5.0 

320 

222. 9 

222. 4 

221.9 

221.5 

221.0 

220.5 

2'20. 0 

219.6 

219. 1 

218.7 

218.2 

217.8 

217.3 

216.9 

216.4 

216. 0 

325 

2'23. 9 

223.4 

222.9 

222.4 

222.0 

221.5 

221. 0 

2'20. 6 

220.1 

219. 6 

219.2 

218.7 

21,8, 3 

217.8 

217.4 

■217. 0 

330 

22-4.8 

224'. 3 

223.8 

223.4 

2'2'2.9 

22^2. 4 

222.0 

■221. 5 

221.1 

■220.6 

2‘20. 2 

219.7 

219. 3 

21.8. 8 

218.4 

21.8, 0 

335 

225.7 

225. 2 

224.8 

224.3 

223.8 

223.4 

222. 9 

2‘22. 5 

■22‘2. 0 

■221. 6 

221.1 

220. 7 

2‘20. 2 

219.8 

219. 4 

21.8. 9 

340 

226.6 

226. 2 

225. 7 

225. 2 

224.8 

221. 3 

223.9 

223. 4 

223.0 

222.5 

2‘22. 1 

221. 6 

■221. 2 

220.8 

2‘20. 3 

■219. 9 

345 

227. 5 

227.1 

226.6 

220. 1 

225.7 

225.2 

224.8 

224.3 

223.9 

223.4 

223.0 

222.6 

222. 1 

221. 7 

■221. 3 

2‘20. 8 

350 

228.4 

227.9 

227.5 

227. 0 

226.6 

226. 1 

225. 7 

■2‘25. 2 

224. 8 

224.4 

2‘23.9 

223. 5 

223. 1 

222. 0 

2'22. 2 

■2‘21. 8 

3.55 

229.3 

228.8 

228.4 

227.9 

227.5 

227.0 

226.6 

2‘26.1 

22.5. 7 

225. 3 

224. 8 

■224. 4 

224.0 

223.6 

2‘23. 1 

222. 7 

360 

230.1 

229.7 

229.2 

228.8 

228. 3 

227.9 

227.5 

2‘27. 0 

■226. 6 

■226. 2 

225.7 

22.5. 3 

■224. 9 

224. 4 

■224. 0 

■2'23. 6 

365 

231. 0 

230.5 

230. 1 

229.0 

229.2 

228.8 

228. 3 

227. 9 

227.5 

227. 0 

■226. 0 

226. 2 

225. 8 

225. 4 

2‘24. 9 

224.5 

370 

231. 8 

231.4 

230. 9 

230.5 

230.1 

229.6 

2'29. 2 

228.8 

228.3 

227.9 

227.5 

227.1 

220. 6 

2‘26. 2 

2'25. 8 

■225. 4 

375 

232. 7 

232.2 

231.8 

231.3 

230.9 

■230. 5 

230.0 

2'29.6 

229.2 

■228. 8 

228.4 

227. 9 

227. 5 

227.1 

220.7 

2‘20. 3 

380 

233.5 

233.0 

232.6 

232. 2 

231. 7 

■2111. 3 

230.9 

230. 5 

2 : 10. 0 

2‘29. 0 

229. 2 

228. 8 

228.4 

228. 0 

227.0 

■2‘27. 2 

38.5 

234. 3 

233. 9 

233.4 

233.0 

232. 6 

23'2. 1 

■231. 7 

231. 3 

■230. 9 

230. 5 

2 : 10. 0 

229. 6 

2‘29. 2 

228.8 

228. 4 

228. 0 

390 

235.1 

234.7 

234. 2 

233.8 

233.4 

232. 9 

232. 5 

232. 1 

231.7 

231. 3 

■230. 9 

230. 5 

230.1 

229.6 

2‘29. 3 

228. 9 

395 

235.9 

235.4 

235.0 

234.6 

234. 2 

233.8 

233.3 

2:12.9 

232.5 

232. 1 

231.7 

231.3 

230.9 

230. 5 

2 : 10 . 1 

■229. 7 

400 

236. 7 

236.2 

235.8 

23.5. 4 

235. 0 

234. 6 

234. 1 

233.7 

■233. 3 

232.9 

232. 5 

232. 1 

231.7 

2.31.3 

230.9 

230. 5 

405 

237. 4 

237.0 

236.6 

230.2 

235. 8 

235. 4 

234.9 

234.5 

‘234. 1 

23:1. 7 

•233. 3 

2 : 12.9 

2 : 12 . 5 

232.1 

231.7 

■2.31. 3 

410 

238. 2 

237. 8 

237.4 

236. 9 

■236. 5 

236. 1 

235.7 

2:15. 3 

■234. 9 

234. 5 

234. 1 

233. 7 

•233. 3 

232. 9 

■232. 5 

■232. 1 

415 

239. 0 

238.5 

238.1 

237. 7 

237. 3 

236. 9 

236. 5 

2:16. 1 

235.7 

■23,5. 3 

‘234. 9 

■234. 5 

■234. 1 

2: i 3. 7 

•233. 3 

•232. 9 

420 

239.7 

239.3 

238. 9 

238. 5 

238.1 

237.6 

237.2 

236.8 

■236. 5 

230. 1 

235.7 

■235. 3 

■234. 9 

234.5 

234. 1 

■233. 7 

425 

• m.i 

240.0 

239. 6 

239. 2 

■238. 8 

238.4 

238. 0 

237. 0 

•237. 2 

2: i 6. 8 

•230. 4 

236.0 

■235. 6 

23.5. 3 

234. 9 

■234. 5 

430 

241.2 

2-10. 8 

240.4 

240. 0 

239. 0 

239. 2 

238. 8 
239. T ) 

238.4 

238. 0 

237. 0 

237. 2 

236. 8 

2 : 16 . 4 

230. 0 

■235. 7 

■235. 3 

435 

iML 9 

241.5 

241. 1 

240.7 

240. 3 

239. 9 

239. ] 

238. 7 

238.3 

238. 0 

■237. 6 

237.2 

2.36. 8 

■236. 4 

■236. 0 

440 

2-12. 6 

2-42.2 

241.8 

241.4 

241. 0 

240. 0 

240. 2 

239. 8 

239. 5 

239. 1 

238. 7 

2:18.3 

237. 9 

2 : 17 . 5 

237.2 

236. 8 

445 

213.3 

212.9 

242. 5 

242.1 

■241. 7 

241.4 

241.0 

2-10.0 

240. 2 

239. 8 

2 : 19. 4 

■ 2 : 19. 0 

2.38.7 

238. 3 

237.9 

■237. 6 




INSTRUCTIONS FOR AFROLOGJC^AL ORSERVKiCS 


111 


Table 26. — Rate of ascent, in meters per minute, for given weight (w) and free lift (1) — Continued. 


4r>o. . 

455 . . 

460 . . 

465 . . 

470 .. 

475 .. 

480 . . 

485 .. 

490 .. 

495 . . 

500 . . 

505 . . 

510 .. 

515 .. 

520 .. 

525 .. 

530 . . 

535 . . 

540 . . 
545 . 

550 . 

555 . 

560 . 

565 . 

570 . 

. 575 . 

580 . 

585 . 

590 .. 

595 . . 

600 . 

605 . 

610 . 

615 . 

620 . 

625 . 

630 . 

635 . 

640 . 

645 . 

650 . 


36 


249.0 
249. 6 
2 . 50. 3 

2 . 50.0 
251 . C 


38 

40 

42 

14 

46 

48 

50 

52 

54 

56 

58 

60 

62 

64 

66 

68 

248.6 

248. 1 

247.7 

247. 3 

246.9 

246.5 

246.0 

245.6 

245. 2 

244.8 

244.4 

244. 0 

243. 6 

243. 2 

242.8 

242.4 

249. 2 

248.8 

248.4 

248.0 

247.5 

247.1 

248.7 

246.3 

245. 9 

245. 5 

245. 1 

2 . 44.7 

244. 3 

243.9 

243. 5 

243.2 

249. 9 

249.5 

249.0 

248.6 

248.2 

247.8 

247.4 

247.0 

246.6 

246.2 

24 . 5. 8 

24 . 5.4 

245.0 

244.6 

244.2 

243.8 

250.5 

2 . 50. 1 

249.7 

249.3 

248.9 

248.5 

248.1 

247.7 

247.3 

246.9 

248. 5 

246.1 

245.7 

24 . 5. 3 

244.9 

244.5 

251.2 

250.8 

250.3 

249.9 

249.5 

249.1 

248.7 

248.3 

247.9 

247.5 

247.2 

246. 8 

246.4 

246.0 

245.6 

245.2 

251. 8 

2 . 51.4 

251.0 

250.6 

250.2 

249.8 

249.4 

249.0 

248.6 

248.2 

247.8 

247.4 

247.0 

246.7 

246.3 

245. 9 

252.4 

252.0 

251.6 

251.2 

250.8 

250.4 

250.0 

249.6 

249.2 

248.9 

248.5 

248. 1 

247.7 

247.3 

247.0 

246.6 

253.0 

2 . 52.7 

252.2 

251.8 

251.5 

251. 1 

250.7 

250.3 

249.9 

249.5 

249.1 

248.8 

248.4 

248.0 

247. 6 

247.2 

253.7 

253.3 

252.9 

252.5 

252.1 

251. 7 

251.3 

2 , 50.9 

2 . 50.5 

250.2 

249.8 

249.4 

249.0 

248.6 

248.3 

247.9 

254.3 

253.9 

253.5 

25 . 3.1 

2 . 52. 7 

252. 3 

251. 9 

251.6 

251.2 

250.8 

250.4 

2 . 50. 0 

249.7 

249.3 

248.9 

248.6 


254.5 

254.1 

253.7 

25 : 1.3 

253.0 

252.6 

2 . 52.2 

251.8 

251.4 

251.0 

2 . 50.7 

250.3 

249.9 

249.6 

249.2 


255.1 

254.7 

254.3 

2 . 53. 9 

253.6 

253.2 

252.8 

252.4 

2 . 52. 1 

251.7 

251. 3 

250.9 

250.6 

250.2 

249.8 


255.7 

255.3 

254.9 

254. 6 

254.2 

253.8 

253. 4 

253.0 

252.7 

252.3 

2 . 51. 9 

2 . 51. 6 

251.2 

250.8 

250.5 


256. 3 

255. 9 

255.5 

2 . 5 , 5. 2 

2 . 54.8 

254.4 

254.0 

253.7 

253. 3 

252.9 

252.6 

252.2 

251.8 

251.5 

251. 1 


256.9 

256.5 

256. 1 

255.8 

255.4 

2 . 55.0 

254.6 

254.3 

253.9 

253.5 

253.2 

252.8 

252.4 

252.1 

251.7 


257.5 

257.1 

256.7 

256.4 

256.0 

255.6 

255.2 

254.9 

254. 5 

254.2 

253.8 

253.4 

253.0 

252.7 

2 . 52. 4 


258.1 

257.7 

257. 3 

2 . 56.9 

256.6 

256. 2 

255. 8 

255. 5 

255.1 

254.7 

254. 4 

2 . 54. 0 

25 : 1.7 

253.3 

253.0 


258.6 

258.3 

257.9 

257.5 

257.2 

2 . 56. 8 

256.4 

2 . 56.0 

255.7 

255.3 

255.0 

254.6 

2 , 54. 3 

253.9 

2 . 53. 6 


259.2 

258.8 

258.5 

258.1 

257.7 

257.4 

2 . 57.0 

256.6 

256.3 

25 . 5.9 

255. 6 

255. 2 

254.9 

254. 5 

254.2 


259.8 

259.4 

259.0 

258.7 

258.3 

258.0 

257.6 

257.2 

256.9 

256.5 

256.2 

255.8 

255.5 

255.1 

254.8 


260.3 

260.0 

259.6 

259.2 

258.9 

258. 5 

258.2 

257.8 

257.4 

257.1 

256. 7 

256.4 

256.0 

255.7 

255.4 


260.9 

260.5 

260.2 

259.8 

259.4 

259.1 

258.7 

258.4 

258.0 

257.7 

257.3 

257.0 

256.6 

256.3 

256.0 


261.4 

261.1 

260.7 

260.4 

260.0 

259.6 

259.3 

259.0 

258.6 

258.2 

257.9 

257. 6 

257.2 

256.9 

256.5 


262.0 

261.6 

261.3 

260.9 

260.6 

260.2 

259.9 

259.5 

259.2 

258.8 

258.5 

258.1 

257.8 

257.4 

257.1 


262.5 

262.2 

261.8 

261.5 

261.1 

260.8 

260.4 

260.1 

259.7 

259.4 

259.0 

258.7 

258.4 

258.0 

257.7 


263. 1 

262.7 

262.4 

262.0 

261.7 

261.3 

261.0 

260.6 

260.3 

259.9 

259.6 

259.3 

258.9 

258. 6 

258.2 


263.6 

263.3 

262.9 

262.6 

262.2 

261.9 

261.5 

261.2 

260.8 

260.5 

260.2 

259.8 

259.5 

259.1 

258.8 


264.2 

263.8 

263.5 

263.1 

262.8 

262.4 

262.1 

261.7 

261.4 

261.0 

260.7 

260.4 

260.0 

259.7 

259.4 


264.7 

264.3 

264.0 

263.6 

263.3 

263.0 

262.6 

262.3 

261.9 

261.6 

261.3 

260. 9 

260.6 

260.3 

259. 9 


265.2 

264.9 

264.5 

264.2 

263.8 

263.5 

263.2 

262.8 

262.5 

262.1 

261.8 

261.5 

261.1 

260.8 

260.5 


265.7 

265.4 

265.0 

264.7 

264.4 

264.0 

263.7 

263.4 

263.0 

262.7 

262.4 

262.0 

261.7 

261.4 

261.0 


266.2 

265.9 

265.6 

265.2 

264.9 

264.5 

264.2 

263.9 

283.5 

263.2 

262. 9 

262.6 

262. 2 

261.9 

261.6 


266.8 

266.4 

266.1 

265.7 

26 . 5.4 

265.1 

264.7 

264.4 

264.1 

263.7 

263.4 

263.1 

262.8 

262.4 

262. 1 


267.3 

266.9 

266.6 

266.3 

26 . 5.9 

265.6 

265.3 

264.9 

264.6 

264.3 

263.9 

263.6 

263. 3 

263.0 

262. 6 


267.8 

267.4 

267.1 

266.8 

266.4 

266.1 

265.8 

265.4 

265.1 

264.8 

264.5 

264.1 

263.8 

263.5 

263. 2 


268.3 

267.9 

267.6 

267.3 

266.9 

266.6 

266.3 

266.0 

265. 6 

265. 3 

265.0 

264.7 

264.3 

264.0 

263.7 


268.8 

268.4 

268.1 

267.8 

267. 4 

267.1 

266.8 

266.5 

266.2 

265.8 

265. 5 

265.2 

264.9 

264.5 

264. 2 


269.3 

268.9 

268.6 

268.3 

268.0 

267.6 

267.3 

267.0 

266.6 

266.3 

266.0 

265.7 

265.4 

265.1 

264.8 


269.8 

269.4 

269.1 

268.8 

268.4 

268.1 

267.8 

267.5 

267.2 

266.8 

266.5 

266.2 

265.9 

265.6 

265. 3 


270.2 

269.9 

269.6 

269.3 

269.0 

268.6 

268.3 

268.0 

267.7 

267.4 

267.0 

266. 7 

266.4 

266.1 

265.8 


270.7 

270.4 

270.1 

269.8 

269. 4 

269.1 

268. 8 

268.5 

268. 2 

267.8 

267.5 

267. 2 

266. 9 

266.6 

206.3 


1 . 

70 

72 

74 

76 

78 

80 

,82 

84 

86 

88 

90 

4.50 

242 . 1 

241.7 

241.3 

240.9 

240.5 

240. 1 

239.8 

239 4 

2 : 19.0 

338.6 

238.3 

455 

242.8 

242.4 

242.0 

•241 6 

241.2 

240 9 

■ 240. 5 

240. 1 

2 : 19.8 

239.4 

239.0 

460 

243 5 

243. 1 

242.7 

242. 3 

242.0 

241.6 

241.2 

■ 240 . 8 

240.5 

240.1 

239.8 

465 

244. 2 

243.8 

243.4 

24 . 3.0 

242.6 

• 242 . 3 

■ 241.9 

• 241.6 

241.2 

240.8 

240.4 

470 

214.8 

244.5 

244.1 

• 213. 7 

243.4 

243.0 

242.6 

■ 24 ^ 2.2 

241.9 

241.5 

241 . 2 

475 

245.5 

24 . 5 . 2 

244.8 

244.4 

• 244.0 

243.7 

24 . 3 . 3 

• 242. 9 

242.0 

24 ^ 2. 2 

211.9 

480 

246 . 2 

245 . 8 

24 . 5.5 

245. 1 

214.7 

214.4 

• 244. 0 

• 24 . 3.6 

243.3 

■ 242. 9 

242 . 0 

485 

240.9 

246.5 

246. 1 

24 . 5. 8 

24 . 5. 4 

215.0 

244.7 

■ 244. 3 

244. 0 

■ 24 : i . 0 

243. 2 

490 

247.5 

247.2 

210 . 8 

246.4 

246. 1 

245 . 7 

245.4 

■ 24 . 5 . 0 

241 0 

214.3 

■ 243. 9 

495 . . 

248.2 

247.8 

247. 5 

• 247 . 1 

240.7 

248 . 4 

■ 246.0 

245. 7 

245.3 

245. 0 

244.0 

.500 

248.8 

248.5 

248. 1 

■ 247 . 8 

247.4 

■ 2 17 . 0 

240.7 

246.3 

■ 240 . 0 

24 . 5 . 6 

215. 3 

505 

249.5 

249 . 1 

248.8 

248 . 4 

248.0 

247.7 

247.3 

247.0 

■ 240. 0 

240 . 3 

24 . 5. 9 

.510 

250. 1 

249.8 

249.4 

219.0 

248.7 

248.3 

248 . 0 

247.0 

■ 247.3 

■ 247 . 0 

• 246. 0 

515 

250.8 

2 , 50 . 4 

250.0 

249.7 

219.3 

249.0 

248. 6 

■ 248 . 3 

248. 0 

247.0 

• 247. 3 

520 

251.4 

251.0 

250.7 

250.3 

250.0 

■ 219 . 6 

219 . 3 

248.9 

248 . 0 

248.2 

247.9 


2 , 52. 0 

251 . 6 

251 , 3 

• 250.9 

2 '> 0. 0 

2 . 50.2 

■ 249 . 9 

■ 249.6 

249.2 

■ 248 . 9 

■ 248.5 

530 

252.6 

252.3 

251.9 

251.6 

251.2 

250.9 

2 . 50 . 5 

250.2 

249 . 8 

249 . 5 

249. 2 

.535 

25 . 3 . 2 

252.9 

• 252. 5 

252 . 2 

251.8 

■ 251.5 

251.2 

2 . 50 . 8 

2 , 50 . 5 

250. 1 

249 . 8 

540 

253 . a 

2 . 5 . 3 . 5 

25 . 3 . 1 

• 252 . 8 

2 . 52 . 4 

■ 252 . 1 

2 . 51.8 

• 251 . 1 

■ 2 i 51 . 1 

2 , 50. 8 

2 ; 50 . 4 

545 

2 . 54. 4 

2 . 54. 1 

253.7 

253.4 

253.0 

252. 7 

• 252 . 4 

■ 252. 0 

■ 2,51 7 

251.4 

251.0 


255. 0 

2 . 54. 7 

• 254 . 3 

2 . 54. 0 

253.6 

253.3 

253.0 

■ 252 . 7 

2 , 52 . 3 

252.0 

251.0 

555 

255. 6 

2 . 5 . 5. 2 

• 2 . 54 . 9 

254.6 

254.2 

25 . 3.9 

2 . 5:1 0 

2, ■'..3. 2 

•2.52. 9 

■252. 6 

•252. 3 

.560 

256.2 

2.5.5. 8 

255.5 

25,5. 2 

2.54. 8 

254.5 

■2.‘ i 4. 2 

253.9 

•2.53. 5 

■25:1 2 

252.9 

565 

2,50. 8 

250.4 

•256. 1 

•25.5. 8 

2.3.'). 4 

255. 1 

■-'.■►1.8 

254.4 

2.54. 1 

253.8 

2.53. 5 


257.3 

257.0 

256.7 

256.3 

2.50.0 

255.7 

2.55. 4 

2.5.5. 0 

251.7 

2.54. 4 

•2,54. 1 


257.9 

257. 6 

2.57. 2 

258.9 

256.0 

2.56. 3 

2.50.0 

2.55. 0 

255, 3 

2.55. 0 

254.0 

.580 

25 H . 5 

258.2 

257.8 

•257. 5 

•257. 2 

2,56.8 

2.56. 5 

250. 2 

255. 9 

•255. 0 

255. 2 

.585 

259.0 

2.58. 7 

258.4 

258. 1 

•257. 7 

2.57. 4 

257. 1 

2.50.8 

250. 5 

2,56. 1 

255. 8 

.590 

259.6 

•2.59. 3 

259.0 

•258. 6 

•258. 3 

2.58. 0 

257.7 

•257.3 

2.57. 0 

2,56. 7 

2.56. 4 

595 

260.2 

259.8 

2 W .5 

•259. 2 

258.8 

•258.5 

•258.2 

257.9 

257.0 

257. 3 

257.0 

600 

200.7 

•200.4 

200. 1 

•256. 7 

259.4 

2.59. 1 

2.58. 8 

2.58. 6 

2.58. 2 

257.8 

2,57. 5 

005 

261.2 

200.9 

200.6 

200.3 

■260. 0 

2.59. 6 

2.59.3 

•259. 0 

258.7 

■258.4 

•258. 1 

610 

281.8 

201.5 

•201. 2 

200.8 

■260.5 

260.2 

2.59. 9 

•2,59. 0 

■2.59. 3 

259. 0 

258. 0 


202.3 

202.0 

•261. 7 

201.4 

■261. 1 

200.8 

260.4 

200. 1 

2.59. 8 

259. 5 

259.2 

620 

262.9 

•202. 5 

202.2 

■201.9 

■261. 0 

■261.3 

■261.0 

200.7 

200.4 

200. 0 

■259. 8 

625 

263.4 

203.1 

•28^2. 8 

■202.4 

•262. 1 

•201.8 

■261. 5 

201.2 

■200.9 

260.0 

■200. 3 


263. V 


20.3. 3 

2 t 53.0 

2 tt 2. 7 

262. 4 

2< i 2. 1 

2( J 1. 7 

*201. 4 

201. 1 

K 

6:i6 

261.4 

204. 1 

•263.8 

■203.5 

■203.2 

•262.9 

202.0 

202.3 

■20^2. 0 

261.7 

■201.4 


28.5.0 

■jiiA. 0 

264.3 

2 m . 0 

■203.7 

•2 o :<.4 

20: i . 1 

202.8 

202.5 

202. 2 

201.9 


205.5 

265.2 

204.8 

2 m . 5 

2 m. 2 

263.9 

■263. 0 

203.3 

203.0 

•202. 7 

20^2. 4 

650 

260.0 

205.7 

265.4 

205.1 

2 m . 8 

•2 m . 5 

2 m. 2 

203.8 

203.0 

203.2 

263.0 


112 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS 


Table 26a . — Rale of ascent, in meters per minute, for weight (w) and free lift (1). 


w. 


i. 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

.36 

37 

38 

39 

40 

7.5 

104 

](>3 

163 

162 

161 

160 

160 

159 

158 

168 

157 

156 

156 

155 

154 

154 

1.53 

153 

1,52 

152 

151 

1.50 

150 

149 

149 

148 

7() 

1(>5 

164 

163 

162 

162 

161 

160 

160 

159 

158 

1,58 

157 

156 

1,56 

1.55 

154 

154 

153 

1.53 

152 

152 

151 

150 

150 

149 

149 

77 

165 

l(i4 

164 

163 

162 

162 

161 

160 

160 

1.59 

158 

158 

157 

150 

156 

1.55 

1.55 

1.54 

1.53 

153 

152 

1,52 

151 

150 

150 

149 

7S 

166 

165 

164 

164 

163 

162 

102 

161 

u\o 

160 

1.59 

158 

158 

157 

156 

15(5 

1.55 

155 

154 

1.53 

153 

1.52 

1.52 

151 

151 

150 

79 

luii 

160 

165 

164 

164 

163 

162 

162 

161 

KiO 

160 

1.59 

158 

158 

157 

156 

150 

155 

155 

154 

154 

153 

1.52 

152 

1.51 

151 

SO 

107 

166 

166 

105 

164 

163 

163 

162 

161 

161 

160 

160 

1.59 

158 

158 

157 

1.57 

1.56 

155 

155 

154 

154 

1.53 

15.3 

152 

152 

SI 

108 

167 

166 

l(i6 

lo5 

164 

163 

163 

162 

161 

161 

160 

160 

159 

1.58 

458 

1.57 

157 

156 

155 

155 

154 

1.54 

153 

153 

152 

S2 

168 

107 

167 

166 

i;i5 

l'-,5 

164 

1()3 

lSi3 

102 

161 

101 

160 

160 

159 

158 

1.58 

157 

157 

1.56 

155 

155 

155 

1.54 

1.53 

153 

S3 

169 

108 

1«M 

ir.T 

166 

165 

105 

164 

163 

103 

162 

161 

1«1 

160 

160 

159 

1.58 

158 

157 

157 

1.56 

156 

155 

155 

154 

15.3 

84 

109 

169 

168 

167 

167 

168 

105 

1(>4 

164 

103 

163 

162 

161 

161 

160 

160 

159 

158 

158 

1.57 

157 

150 

1.56 

loo 

1.55 

154 

8.5 

170 

169 

168 

168 

167 

IfiO 

100 

165 

1(H 

164 

163 

ua 

162 

161 

161 

ifin 

160 

159 

1.58 

1.58 

157 

157 

156 

1.56 

155 

1.55 

80 

170 

170 

169 

168 

168 

167 

106 

166 

165 

164 

164 

16.3 

16.3 

If, 3 

161 

161 

100 

160 

159 

1.58 

158 

1.57 

157 

156 

156 

155 

87 

171 

170 

169 

169 

108 

168 

107 

166 

166 

165 

164 

164 

163 

163 

162 

161 

161 

160 

160 

159 

159 

158 

158 

157 

156 

1.56 

8S 

171 

171 

170 

169 

169 

168 

107 

167 

106 

166 

105 

164 

164 

163 

163 

162 

161 

161 

100 

160 

159 

1.59 

158 

158 

1.57 

156 

89 

172 

171 

170 

170 

169 

169 

168 

167 

167 

166 

165 

165 

164 

104 

163 

162 

162 

161 

161 

160 

160 

1.59 

159 

158 

158 

157 

90 

172 

172 

171 

170 

170 

169 

169 

168 

167 

167 

166 

165 

165 

164 

lfi4 

163 

163 

162 

161 

161 

160 

160 

159 

1,59 

1.58 

15S 

91 

173 

172 

171 

171 

170 

170 

169 

168 

168 

167 

167 

166 

165 

165 

164 

164 

163 

103 

162 

161 

161 

160 

KiO 

159 

159 

158 

92 

173 

173 

172 

171 

171 

170 

170 

169 

168 

168 

167 

167 

1(',6 

165 

165 

104 

164 

163 

163 

162 

161 

161 

K*0 

160 

159 

1.59 

93 

174 

173 

173 

172 

171 

171 

170 

169 

109 

168 

168 

1()7 

167 

166 

165 

165 

164 

164 

163 

163 

162 

162 

161 

161 

luO 

159 

94 

174 

174 

173 

172 

172 

171 

171 

170 

109 

169 

168 

168 

167 

106 

166 

105 

105 

164 

164 

163 

103 

162 

162 

161 

101 

160 

95 

175 

174 

174 

173 

172 

172 

171 

170 

170 

169 

169 

168 

168 

167 

166 

166 

165 

165 

164 

164 

163 

B'>3 

162 

162 

161 

161 

9(; 

175 

175 

174 

174 

173 

172 

172 

171 

170 

170 

169 

169 

168 

107 

167 

166 

160 

105 

165 

KU 

164 

163 

163 

162 

162 

161 

97 

176 

175 

175 

174 

173 

173 

172 

171 

171 

170 

170 

169 

169 

168 

167 

107 

166 

166 

165 

IG5 

164 

104 

163 

163 

102 

162 


170 

176 

175 

174 

174 

173 

173 

172 

171 

171 

170 

170 

169 

169 

168 

167 

167 

166 

166 

105 

105 

164 

164 

103 

1()3 

102 

99 

177 

176 

176 

175 

174 

174 

173 

172 

172 

171 

171 

170 

170 

169 

168 

168 

167 

107 

160 

100 

105 

165 

164 

104 

163 

KkJ 

100 

177 

177 

170 

175 

175 

174 

174 

173 

172 

172 

171 

171 

170 

170 

109 

168 

168 

107 

167 

106 

160 

105 

165 

164 

164 

163 

101 

178 

177 

177 

176 

175 

175 

174 

174 

173 

172 

172 

171 

171 

170 

169 

169 

108 

168 

167 

167 

160 

IGfi 

lt)5 

1G5 

l(i4 

164 

102 

178 

178 

177 

176 

176 

175 

175 

174 

173 

173 

172 

173 

171 

171 

170 

169 

169 

168 

108 

167 

167 

106 

100 

1G5 

165 

164 


179 

178 

177 

177 

176 

176 

175 

174 

174 

173 

173 

173 

172 

171 

171 

170 

169 

169 

168 

168 

167 

167 

160 

166 

KiO 

165 

104 

179 

178 

ITS 

177 

177 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

170 

170 

109 

109 

168 

108 

167 

107 

106 

100 

166 

105 

180 

179 

178 

178 

177 

177 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

170 

170 

KiO 

169 

168 

168 

167 

107 

167 

166 

1()(J 

180 

179 

179 

178 

178 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

171 

171 

170 

170 

169 

169 

168 

168 

167 

167 

11)7 

107 

180 

180 

179 

179 

178 

177 

177 

176 

176 

175 

175 

174 

174 

173 

172 

172 

171 

171 

170 

170 

169 

169 

108 

168 

168 

167 

108 

181 

180 

180 

179 

178 

178 

177 

177 

17G 

176 

175 

175 

174 

174 

173 

172 

172 

171 

171 

170 

170 

109 

169 

108 

168 

167 

109 

181 

181 

180 

ISO 

179 

178 

178 

177 

177 

176 

176 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 

170 

109 

109 

168 

108 

110 ’ 

182 

181 

181 

180 

179 

179 

178 

178 

177 

177 

176 

176 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 

170 

109 

169 

108 

Ill 

182 

182 

181 

1,80 

180 

179 

179 

178 

177 

177 

17G 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 

170 

169 

169 

112 

183 

182 

181 

181 

180 

180 

179 

179 

178 

177 

177 

176 

170 

175 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 

170 

169 

113 

183 

182 

182 

181 

181 

180 

180 

179 

178 

178 

177 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 

170 

114 

183 

183 

182 

182 

181 

181 

180 

ISO 

179 

178 

178 

|l77 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

171 

170 



\v. 


15 

10 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

115 

184 

183 

183 

182 

182 

181 

181 

ISO 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

171 

116 

184 

184 

183 

183 

182 

181 

181 

ISO 

180 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

172 

171 

117 

185 

181 

184 

183 

1.82 

182 

181 

181 

180 

180 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

174 

174 

173 

173 

172 

172 

118 

185 

184 

184 

183 

183 

182 

182 

181 

181 

180 

ISO 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

174 

171 

173 

173 

172 

119 

185 

185 

1.84 

184 

183 

183 

182 

182 

181 

181 

ISO 

180 

179 

178 

178 

177 

177 

176 

176 

175 

175 

175 

174 

174 

173 

173 

120 

186 

185 

185 

184 

184 

183 

183 

182 

182 

181 

180 

180 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

175 

174 

174 

173 

121 

180 

186 

185 

185 

184 

183 

183 

182 

182 

IHl 

181 

ISO 

180 

179 

179 

178 

178 

177 

177 

17G 

17G 

175 

175 

175 

174 

174 

122 

187 

186 

186 

185 

184 

184 

183 

183 

182 

182 

181 

181 

180 

180 

179 

179 

178 

178 

177 

177 

176 

176 

175 

175 

175 

174 

123 

187 

1.86 

186 

185 

185 

184 

184 

183 

183 

182 

1,82 

181 

181 

1,80 

180 

179 

179 

178 

178 

177 

177 

170 

17G 

175 

175 

175 

121 

187 

187 

180 

186 

185 

185 

184 

184 

183 

183 

182 

182 

181 

181 

180 

ISO 

179 

179 

178 

178 

177 

177 

176 

170 

175 

175 


188 

187 

187 

ISG 

186 

185 

185 

184 

1.84 

183 

183 

182 

182 

181 

181 

180 

ISO 

179 

179 

178 

178 

177 

177 

170 

176 

175 

126 

188 

188 

187 

187 

186 

185 

185 

184 

184 

183 

1.83 

182 

182 

181 

181 

1.80 

180 

180 

179 

179 

178 

178 

177 

177 

176 

176 

127 

189 

188 

188 

187 

186 

186 

185 

185 

184 

184 

1,83 

183 

182 

182 

181 

181 

180 

180 

180 

179 

178 

178 

178 

177 

177 

17G 

128 

189 

188 

188 

187 

187 

186 

186 

185 

185 

184 

184 

183 

183 

182 

182 

IHl 

LSI 

180 

180 

179 

179 

178 

178 

177 

177 

n? 

129 

189 

189 

188 

188 

187 

187 

186 

186 

185 

185 

184 

184 

183 

183 

182 

182 

181 

181 

ISO 

ISO 

179 

179 

178 

178 

177 

177 

130 

190 

189 

189 

188 

188 

187 

186 

180 

185 

185 

184 

184 

184 

IH3 

183 

182 

182 

181 

181 

180 

ISO 

179 

179 

178 

178 

177 

131 

190 

190 

189 

188 

188 

187 

187 

ISO 

186 

185 

185 

184 

184 

183 

183 

182 

182 

181 

181 

181 

180 

180 

179 

179 

17S 

17S 


190 

190 

1,89 

1H9 

188 

188 

187 

1.S7 

186 

1,80 

185 

185 

184 

184 

183 

183 

182 

1.82 

181 

181 

181 

180 

ISO 

17'> 

179 

17S 

133 

191 

190 

190 

189 

189 

188 

188 

187 

187 

186 

ISO 

185 

185 

1,84 

184 

183 

183 

1.82 

182 

1,81 

181 

ISl 

180 

ISO 

179 

179 

134 

191 

191 

190 

190 

189 

188 

188 

187 

187 

186 

186 

185 

185 

185 

184 

184 

183 

183 

182 

1S2 

1.81 

1.81 

181 

180 

ISO 

179 

135 

192 

191 

190 

190 

189 

189 

188 

188 

187 

187 

180 

180 

185 

1.S5 

185 

184 

184 

1,83 

183 

182 

182 

181 

181 

180 

1.80 

ISO 

130 

192 

191 

101 

190 

190 

189 

189 

188 

188 

187 

187 

IHG 

ISO 

185 

185 

181 

181 

181 

LS3 

183 

182 

IS2 

1.81 

ISl 

ISO 

l.SO 

137 

192 

192 

191 

191 

190 

190 

189 

189 

188 

188 

187 

187 

ISG 

1.86 

185 

185 

184 

184 

1,83 

183 

183 

182 

1.82 

ISl 

isl 

ISO 

138 

193 

192 

191 

191 

190 

190 

189 

189 

189 

188 

188 

187 

186 

180 

186 

185 

185 

184 

IcSl 

1,83 

IKi 

182 

1S2 

1S2 

ISl 

181 

139 

193 

192 

192 

191 

191 

190 

190 

189 

189 

183 

188 

187 

1,87 

186 

IHG 

185 

185 

185 

184 

184 

183 

183 

1.82 

182 

1S2 

ISI 

140 

193 

193 

192 

192 

191 

191 

190 

190 

189 

isy 

188 

188 

187 

187 

186 

186 

185 

1S5 

186 

1.81 

184 

183 

1.83 

182 

182 

182 

141 

194 

193 

192 

192 

191 

191 

190 

190 

190 

189 

189 

188 

188 

187 

187 

ISG 

ISG 

1S5 

185 

1.85 

184 

1S4 

1S3 

1S3 

IS2 

l.s2 

142 

194 

193 

19:} 

192 

192 

191 

191 

190 

190 

189 

189 

189 

ISK 

188 

187 

187 

186 

ISG 

18;‘) 

185 

184 

ISl 

1S4 

is:i 

is;} 

1S2 

143 

194 

194 

193 

193 

192 

192 

191 

191 

190 

190 

189 

189 

1H8 

ISH 

1H8 

187 

187 

IHG 

186 

18,5 

IS.") 

IvSl 

IS4 

IS4 

iSH 

isii 

144 

195 

194 

191 

193 

193 

192 

192 

191 

191 

190 

190 

189 

189 

IHS 

18H 

187 

187 

IHG 

186 

1.86 

185 

1H5 

ISl 

ISl 

ivsa 

Sii 

115 

195 

194 

194 

193 

193 

192 

192 

191 

191 

191 

190 

190 

189 

1.89 

188 

188 

187 

187 

180 

180 

180 

185 

1S5 

184 

1S4 

181 

140 

195 

195 

194 

191 

193 

193 

192 

192 

191 

191 

190 

190 

189 

189 

189 

188 

188 

187 

1.87 

IHG 

ISO 

ISG 

1.85 

ISo 

ISl 

ISI 

147 

190 

195 

194 

194 

194 

193 

193 

192 

192 

191 

191 

190 

190 

189 

m 

1,89 

188 

188 

1.87 

1.87 

IK(> 

ISG 

IS5 

iSf) 

IS5 

ISI 

118 

190 

195 

195 

191 

ly-t 

193 

193 

192 

192 

192 

191 

191 

lUO 

190 

IHU 

1.S9 

188 

ISH 

IMS 

1.87 

1S7 

ISG 

ISG 

1S5 

IS5 

1 S5 

149 

190 

19G 

195 

195 

191 

194 

193 

193 

192 

192 

191 

191 

190 

190 

190 

189 

1.89 

IMS 

ISH 

1S7 

1H7 

IH7 

IHG 

IHG 

185 


1.50 

197 

190 

190 

195 

195 

194 

194 

193 

193 

192 

192 

191 

191 

190 

190 

190 

189 

189 

ISH 

188 

1.87 

IK7 

187 

ISG 

186 

1,85 

151 

197 

lUG 

190 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

190 

190 

1.S9 

1,89 

isy 

IHS 

188 

187 

IS7 

ISG 

IHG 

ISG 


197 

197 

190 

i9G 

195 

195 

194 

194 

193 

193 

192 

192 

192 

191 

191 

190 

190 

189 

IH9 

189 

188 

18S 

187 

187 

ISG 

ISG 

153 

198 

197 

197 

lUG 

m 

195 

195 

194 

194 

193 

193 

192 

192 

191 

191 

191 

190 

190 

1,89 

IH9 

IHS 

ISS 

ISH 

187 

IS7 

ISG 

154 

198 

197 

197 

19G 

196 

195 

m 

194 

191 

194 

193 

193 

192 

192 

191 

191 

190 

190 

190 

1S9 

isy 

188 

IHS 



188 

1S7 

1S7 


INSTRUCTIONS FOR AEROLOGICAL OBSERVPniS. 

Table 2Ga . — Rate of ascent, in meters per minute, for weight (w) and free lift (1) — Conliiiiied. 


I 13 



w . 


15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

156 

198 

198 

197 

197 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

190 

190 

190 

189 

189 

188 

188 

188 

187 


198 

198 

197 

197 

197 

196 

196 

195 

195 

194 

194 

193 

193 

192 

192 

192 

191 

191 

190 

liK ) 

189 

189 

189 

188 

188 

187 

167 

199 

198 

198 

197 

197 

196 

196 

195 

195 

194 

194 

194 

193 

193 

192 

192 

192 

191 

191 

190 

190 

189 

189 

189 

188 

188 

L 68 

199 

199 

198 

198 

197 

197 

196 

196 

195 

195 

194 

194 

194 

193 

193 

192 

192 

191 

191 

191 

190 

190 

189 

189 

189 

188 


199 

199 

198 

198 

197 

197 

197 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

191 

190 

190 

189 

189 

189 

160 

200 

199 

199 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

190 

190 

190 

189 

189 

161 

200 

199 

199 

199 

198 

198 

197 

197 

196 

196 

195 

195 

195 

194 

194 

193 

193 

192 

192 

192 

191 

191 

190 

190 

190 

189 

162 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

195 

195 

194 

194 

194 

193 

193 

192 

192 

192 

191 

191 

190 

190 

190 

163 

201 

200 

200 

199 

199 

198 

198 

197 

197 

197 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

191 

190 

190 


201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

191 

190 

185 

201 

201 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

195 

195 

195 

194 

194 

193 

193 

193 

192 

192 

191 

191 

191 

166 

202 

201 

200 

200 

200 

199 

199 

198 

198 

197 

197 

197 

196 

196 

195 

195 

194 

194 

194 

193 

193 

192 

192 

192 

191 

191 

167 

202 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

196 

196 

198 

195 

195 

194 

194 

194 

193 

193 

192 

192 

192 

191 

168 

202 

202 

201 

201 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

194 

193 

193 

193 

192 

192 

192 

169 

202 

202 

202 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

195 

195 

195 

194 

194 

193 

193 

193 

192 

192 

170 

203 

202 

202 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

197 

196 

196 

195 

195 

195 

194 

194 

193 

193 

193 

192 

171 

203 

203 

202 

202 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

196 

190 

196 

195 

195 

194 

194 

194 

193 

193 

192 

172 

203 

203 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

194 

194 

193 

193 

173 

204 

203 

203 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

194 

193 

193 

174 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

197 

196 

196 

195 

195 

195 

194 

194 

193 

175 

204 

204 

203 

203 

202 

202 

201 

201 

201 

200 

200 

199 

199 

198 

198 

198 

197 

197 

197 

190 

196 

195 

195 

195 

194 

194 

176 

204 

204 

204 

203 

203 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

19-1 

177 

205 

204 

204 

203 

203 

203 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

195 

195 

194 

178 

205 

204 

204 

204 

203 

203 

202 

202 

201 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

197 

1 % 

196 

190 

195 

195 

179 

205 

205 

204 

204 

203 

203 

203 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

197 

190 

196 

195 

195 

180 

206 

205 

205 

204 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

197 

196 

196 

195 

181 

206 

105 

205 

104 

204 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

199 

199 

199 

198 

198 

198 

197 

197 

196 

196 

196 

182 

206 

206 

205 

205 

201 

204 

203 

203 

203 

202 

202 

201 

201 

201 

200 

200 

199 

199 

199 

198 

198 

197 

197 

197 

196 

196 

183 

206 

206 

205 

205 

205 

201 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

199 

198 

198 

197 

197 

197 

196 

184 

207 

206 

206 

205 

205 

204 

201 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

197 

185 

207 

206 

206 

206 

205 

205 

204 

204 

203 

203 

203 

202 

202 

201 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

197 

197 

186 

207 

207 

206 

206 

205 

205 

205 

204 

204 

203 

203 

203 

202 

202 

201 

201 

201 

200 

200 

199 

199 

199 

198 

198 

198 

197 

187 

207 

207 

206 

206 

206 

205 

205 

204 

204 

2 (M 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

199 

198 

198 

198 

188 

208 

207 

207 

206 

206 

205 

205 

205 

204 

204 

203 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

198 

198 

198 

189 

208 

207 

207 

207 

206 

206 

205 

205 

205 

204 

204 

203 

203 

203 

202 

202 

201 

201 

201 

200 

200 

200 

199 

199 

198 

198 

190 

208 

208 

207 

207 

206 

206 

206 

205 

205 

204 

204 

204 

203 

203 

203 

202 

202 

201 

201 

201 

200 

200 

199 

199 

199 

198 

191 

208 

208 

208 

207 

207 

206 

206 

206 

205 

205 

204 

204 

204 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

199 

192 

209 

208 

208 

207 

207 

207 

206 

206 

205 

205 

205 

204 

204 

203 

203 

203 

202 

202 

202 

201 

201 

200 

200 

200 

199 

199 

193 

209 

208 

208 

208 

207 

207 

206 

206 

206 

205 

205 

204 

204 

204 

2 a 3 

203 

203 

202 

202 

201 

201 

201 

200 

200 

200 

199 

194 

209 

209 

208 

208 

207 

207 

207 

206 

206 

205 

205 

205 

204 

204 

204 

203 

203 

202 

202 

202 

201 

201 

201 

200 

200 

200 















w . 














15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 


209 

209 

209 

208 

208 - 

207 

207 

207 

206 

206 

205 

205 

205 

204 

204 

204 

203 

203 

202 

202 

202 

201 

201 

201 

200 

200 

196 

210 

209 

209 

208 

208 

208 

207 

207 

206 

206 

206 

205 

205 

2 a 5 

204 

204 

203 

203 

203 

202 

202 

202 

201 

■201 

■ 21 H ) 

200 

197 

210 

210 

209 

209 

208 

208 

207 

207 

207 

206 

206 

206 

205 

205 

■204 

201 

■201 

203 

203 

203 

■202 

202 

202 

■201 

201 

200 

198 

210 

210 

209 

209 

209 

208 

208 

207 

207 

207 

206 

206 

205 

205 

•205 

204 

204 

204 

203 

203 

202 

■202 

202 

201 

201 

■201 

199 

210 

210 

210 

209 

209 

208 

208 

208 

207 

207 

206 

206 

206 

205 

205 

205 

20-1 

204 

■204 

■203 

■203 

202 

202 

202 

201 

■201 

200 

211 

210 

210 

210 

200 

209 

208 

208 

207 

207 

207 

206 

206 

206 

205 

205 

■ 20-1 

■204 

204 

203 

■203 

202 

202 

202 

202 

201 

201 

211 

211 

210 

210 

209 

209 

208 

208 

208 

207 

207 

207 

206 

206 

206 

2 a 5 

2 a 5 

204 

20-1 

204 

■203 

203 

203 

202 

202 

■202 

202 

211 

211 

210 

210 

210 

209 

209 

208 

208 

208 

207 

207 

206 

206 

206 

205 

205 

2 a 5 

204 

204 

■201 

■203 

■203 

203 

202 

202 

203 

211 

211 

211 

210 

210 

209 

209 

209 

208 

208 

207 

207 

207 

206 

2 C )6 

206 

205 

205 

205 

204 

■204 

■203 

203 

203 

■202 

202 

204 

212 

211 

211 

210 

210 

210 

209 

209 

208 

208 

208 

207 

207 

207 

206 

206 

205 

205 

205 

204 

204 

204 

203 

■203 

203 

202 


212 

211 

211 

211 

210 

210 

210 

209 

209 

208 

208 

208 

•207 

207 

206 

206 

■206 

205 

20.5 

205 

■201 

204 

204 

203 

203 

203 

206 

212 

212 

211 

211 

211 

210 

210 

209 

209 

209 

208 

208 

■207 

207 

■207 

206 

206 

206 

205 

■205 

205 

201 

201 

■204 

■203 

■203 

207 

212 

212 

212 

211 

211 

210 

210 

210 

209 

209 

208 

208 

208 

207 

■207 

■207 

206 

206 

206 

■205 

■205 

■205 

204 

204 

■204 

203 

208 

213 

212 

212 

211 

211 

211 

210 

210 

210 

209 

209 

208 

208 ' 

208 

207 

207 

207 

206 

206 

2 a 5 

205 

20,5 

■201 

204 

■204 

■203 

209 

213 

212 

212 

212 

211 

211 

211 

210 

210 

209 

209 

209 

■208 

208 

208 

207 

■207 

■206 

206 

206 

205 

205 

205 

201 

■JOl 

■204 

210 

213 

213 

212 

212 

212 

211 

211 

210 

210 

210 

209 

209 

208 

208 

208 

■207 

207 

207 

206 

206 

206 

205 

205 

■205 

204 

204 

211 

213 

213 

213 

212 

212 

211 

211 

211 

210 

210 

210 

209 

■209 

208 

■208 

■208 

207 

207 

207 

■206 

206 

206 

205 

205 

205 

204 


214 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

209 

209 

209 

208 

208 

208 

■207 

■207 

207 

20 () 

206 

206 

205 

205 

201 


214 

213 

213 

213 

212 

212 

212 

211 

211 

210 

210 

210 

209 

209 

209 

■208 

208 

208 

207 

207 

■206 

206 

206 

205 

■205 

2 )' 

214 

214 

214 

213 

213 

213 

212 

212 

211 

211 

211 

210 

210 

210 

•Mi 

209 

■208 

■208 

208 

207 

207 

207 

■206 

206 

206 

■205 

■205 


214 

214 

214 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

209 

2041 

208 

208 

■208 

207 

207 

207 

20 (i 

206 

206 ) 

205 

216 

215 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

210 

210 

210 

209 

2 ( K ) 

2041 

208 

208 

208 

■207 

207 

207 

■206 

■206 

200 

217 

215 

214 

214 

214 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

209 

209 

209 

208 

208 

208 

■207 

207 

21 >6 

206 

206 

218 

215 

215 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

209 

2 ( V ) 

208 

208 

■208 

207 

■207 

■207 

■206 

■206 

219 

215 

215 

215 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

209 

209 

■209 

■208 

208 

208 

207 

■207 

207 

■206 

220 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

211 

211 

211 

210 

210 

210 

209 

209 

200 

208 

208 

208 

■207 

207 

■207 

221 

216 

215 

215 

215 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

2 ( K ) 

209 

208 

20 H 

208 

207 

207 

■207 

222 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

209 

209 

2 ( H > 

208 

208 

208 

■207 

■207 

223 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

209 

209 

209 

208 

208 

■208 

207 

224 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

212 

212 

212 

211 

211 

211 

210 

■210 

210 

■209 

■209 

209 

208 

■208 

208 

22.5 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

■212 

211 

211 

211 

210 

210 

210 

209 

209 

208 

■208 

■208 

226 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

■212 

■211 

211 

211 

210 

210 

210 

209 

209 

■209 

208 

208 

227 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

■211 

■210 

210 

210 

209 

209 

■209 

208 

228 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

■210 

210 

210 

209 

209 

209 

229 

218 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

209 

209 

200 

230 

218 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

■211 

210 

210 

210 

209 

209 

231 

218 

218 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

■211 

■211 

210 

210 

210 

■209 

232 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

210 

210 

233 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

■212 

212 

212 

211 

■211 

211 

210 

210 

■210 

234 

219 

218 

218 

218 

217 

217 

216 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

■212 

212 

■212 

■211 

211 

211 

210 

210 


4G32»— 21 8 


114 


INSTRUCTIONS FOR AEROLOGICAL OBSERVERS. 

Table 26a . — Bale of ascent, in melers per minute, for weight (w) and free lift (1) — Continued. 


w. 


i. 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

235 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

210 

236 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

212 

211 

211 

211 

237 

219 

219 

219 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

211 

238 

220 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

2L5 

215 

215 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

211 

239 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

214 

213 

213 

213 

212 

212 

212 

211 

240 

220 

220 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

2,14 

214 

214 

213 

213 

213 

212 

212 

212 

212 

241 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

515 

214 

214 

214 

2,13 

213 

213 

212 

212 

212 

242 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

214 

214 

214 

214 

213 

213 

213 

212 

212 

243 

221 

220 

220 

220 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

213 

212 

244 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

212 

245 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

213 

246 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

214 

213 

213 

247 

221 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

213 

248 

222 

221 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 

213 

249 

222 

221 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

216 

215 

215 

215 

214 

214 

214 

150 

222 

222 

221 

221 

221 

220 

220 

220 

219 

219 

219 

218 

218 

218 

217 

217 

217 

216 

216 

216 

215 

215 

215 

214 

214 

214 


Table 21 —Altitude time tables for various rates of ascent. 
[Ascen.sional rate in meters per minute.] 


Minutes. 

140 

150 

160 

170 

180 

190 

200 

210 

220 

230 

210 

250 

260 

270 

1 

168 

180 

192 

204 

216 

228 

240 

252 

264 

276 

288 

300 

312 

324 

2 

322 

345 

368 

201 

414 

437 

460 

483 

506 

529 

.552 

575 

.598 

621 

3 

476 

510 

544 

578 

612 

646 

680 

714 

748 

782 

816 

850 

884 

918 

4 

623 

668 

712 

756 

801 

846 

890 

934 

979 

1.024 

1,068 

1,112 

1, 1,57 

1,202 


770 

825 

880 

9.55 

990 

1,045 

1, 100 

1, 1.55 

1, 210 

1,265 

1,320 

1,375 

1, 430 

1,485 

6 

910 

975 

1,040 

1, 105 

1,170 

1,235 

1,300 

1,365 

1,430 

1, 49.5 

1,560 

1,625 

1,690 

1,7,55 

7 

1,0.50 

1, 125 

1,200 

1,275 

1,3.50 

1,425 

1,500 

1,575 

1,6.50 

1, 725 

1,800 

1, 875 

1, 9,50 

2, 025 

8 

1,190 

1,275 

1,360 

1,445 

1,530 

1,615 

1,700 

1,7.85 

1,870 

1, 955 

2,040 

2,125 

2,210 

2,295 

9 

1,330 

1, 425 

1,520 

1, 615 

1,710 

1, 805 

1,900 

1,995 

2,090 

2, 185 

2,280 

2,375 

2,470 

2, 505 

10 

1,470 

1,575 

1,680 

1,785 

1,890 

1,995 

2,100 

2, 205 

2,310 

2,415 

2, 520 

2,625 

2,730 

2,835 

11 

1,610 

1,725 

i,m 

1,955 

2,070 

2,185 

2,300 

2,415 

2, 5.30 

2,645 

2,760 

2,875 

2, 990 

3,105 

12 

1,7.50 

1,875 

2,000 

2, 125 

2, 250 

2,375 

2,500 

2, 625 

2,750 

2,875 

3,000 

3,125 

3, 2.50 

3,375 

13 

1,890 

2,025 

2, 160 

2,295 

2,430 

2, 565 

2, 700 

2,8:15 

2,970 

3,105 

3, 2.40 

3,375 

3, 510 

3,645 

14 

2.030 

2,175 

2, 320 

2, -165 

2,610 

2,755 

2,900 

3, 045 

3,190 

3, 335 

3, 480 

3, 625 

3,770 

3,915 

15 

2,170 

2,325 

2,480 

2,635 

2,790 

2,945 

3,100 

3,255 

3, 410 

3, oG5 

3,720 

3,875 

4,0.30 

4,185 

16 

2,310 

2, 475 

2,640 

2,805 

2,970 

3, 1.35 

3,300 

3, 405 

3,630 

3, 795 

3, 960 

4,125 

4,290 

4, 455 

17 

2,4.50 

2, 625 

2,800 

2,975 

3, 150 

3, .325 

3,500 

3,675 

3, 8.50 

4, 025 

4, 200 

4, 375 

4, ,550 

4,725 

18 

2,590 

2,775 

2, 960 

3, 145 

3, .330 

3,515 

3,700 

3, 885 

4, 070 

4,255 

4,440 

4, 625 

4,810 

4,995 

19 

2,730 

2,925 

3,120 

3,315 

3, ,510 

3,705 

3,900 

4, 095 

4,290 

4, 485 

1,680 

1,875 

5,070 

5, 265 

20 

2,870 

3,075 

3,280 

3,485 

3,690 

3,895 

4, 100 

4, 205 

4,610 

4, 715 

4,920 

5,125 

5,330 

5, 535 

21 

3,010 

3, 225 

3,440 

3,6.55 

3,870 

4,085 

4, ,300 

4,515 

4,730 

4, 945 

5, 160 

0, 375 

.5, 590 

5,805 

22 

3, 150 

3,375 

3,600 

3, 825 

4, 0.50 

4,275 

4, 500 

4,725 

4,950 

5, 175 

5, 400 

5, 625 

5, ,»50 

6, 075 

23 

3,290 

3,525 

3,760 

3,995 

4,250 

4,465 

4,700 

4,935 

5, 1 70 

5,405 

5,640 

5, ,875 

6,110 

6,345 

24 

3, 430 

3,675 

3,920 

4, 165 

4, 410 

4,6.55 

4, 900 

5, 145 

.5,390 

5, 635 

5, .880 

6, 125 

6, 370 

G, G15 

25 

3, 570 

3, 825 

4,080 

4,335 

4. 590 

4,845 

5, 100 

5,355 

5,610 

5, 865 

6, 120 

6,375 

G, GoO 

G, 8S5 

23 

3,710 

3,975 

4,2-40 

4, .505 

4,770 

5,035 

5,300 

5, 565 

5, 8.30 

6, 095 

6,360 

6,625 

6, 890 

7, 1,55 

27 

3,8.50 

4, 125 

4,400 

4,675 

4,950 

5, 225 

5, 500 

5,775 

6,0.50 

6, 325 

6, 600 

6, 875 

7,150 

7,425 

28 

3,990 

4,275 

4,560 

4, 845 

5, 130 

5,415 

5,700 

5,98.5 

6,270 

6,5.55 

6, 840 

7,125 

7, 410 

7,695 

29 

4, 130 

4, 425 

4,720 

5,015 

5, .310 

5, 605 

5, 900 

6, 195 

6. 490 

6, 7S5 

7,0,80 

7, 375 

7,670 

7, 965 

30 

4,270 

4, .575 

4,880 

6, 185 

5, 490 

5,795 

6, 100 

6, 405 

6,710 

7,015 

7, :i20 

7, 625 

7, 930 

8,235 

31 

4,410 

4,725 

5,040 

5, .355 

5,670 

5, 985 

6, 300 

6, 615 

6, 9:!0 

7, 21,5 

7, .560 

7, ,875 

.8, 190 

8, 505 

32 

4,550 

4, 875 

5,200 

5, 525 

.5, 850 

6, 175 

6, 500 

6,825 

7, 1,50 

7, 475 

7,800 

8, 125 

8, 450 

8,775 


4,690 

5,025 

.5,360 

5,695 

6,930 

6, 365 

6, 700 

7, 0J5 

7, 370 

7,705 

8, 040 

8, 375 

8,710 

9,045 


4,830 

5, 175 

5, 520 

5, 865 

6,210 

6, 5.5.5 

0, 900 

7, 245 

7, 590 

7, 935 

s, 2sa 

8,62.5 

8,970 

9, 315 

35 

4,970 

5, 325 

.5,680 

6,035 

6,390 

0, 745 

7, 100 

7, 455 

7, 810 

8, 165 

8,520 

8, 875 

9,2:;o 

9, 585 

36 

.5,110 

5, 475 

5, 840 

6,205 

6,570 

6, 93.5 

7,300 

7, 665 

8. 030 

8, .395 

8, 760 

9, 125 

9, 490 

0, 855 

?7 

.5,250 

5,625 

6,000 

8,375 

6,7.50 

7, 125 

7,500 

7,875 

8,2.50 

8,625 

9, 000 

9, 375 

9, 7.50 

10, 125 

38 

5,390 

5, 775 

6, 100 

6, 545 

6, 930 

7,315 

7, 700 

8,085 

8, 470 

8, 855 

9,240 

9, 625 

10.010 

10,395 

39 

.5,530 

6, 925 

6, 320 

6, 715 

7,110 

7, 505 

7, 900 

8,295 

8, 690 

9,085 

9, ISO 

9, .875 

10. 270 

10.665 

40 

5,670 

6, 075 

6, 480 

6, 885 

7, 290 

7,695 

8, 100 

8, 505 

8,910 

0,315 

9,720 

10,125 

10,530 

10,935 


TNSTRIKTIONS FOR AJCRX)L()(JI(^AL OBSERVERS 


115 


TAm,E28 . — Free lift for definite inflation, for ratdf of ascent 140, 100, I,W, 
iOO, !£0, 240, and 260 meters per minute. 


llnto-s of a-soent 

140 

100 

180 

200 

220 

240 

200 

w . 

1. 

1. 

1. 

1. 

1. 

1. 

1. 

15 

43. 8 

68. 6 

106. 0 

161 . 1 

210.4 



16 

44.8 

69.8 

107. 3 

162.6 

242. 1 



17 

4.'). 7 

71.0 

108.7 

164. 2 

243.8 



IR 

4( i . 7 

72.2 

110.0 

165. 7 

245.5 



19 

47.0 

73. .3 

111.4 

107.2 

247.1 



20 

48.5 

74.4 

112.7 

168.7 

248.7 



21 

49.4 

75.5 

114.0 

170.1 

250.3 



22 

50.3 

76.5 

115.3 

171.6 

251. 9 



23 

51.2 

77.6 

116.5 

173.1 

253.5 



24 

52.0 

78.7 

117.8 

174.5 

255. 1 




52. 8 

79.7 

119.0 

175. 9 

256. 6 



2 t ) 

53. 0 

80.7 

120. 2 

177. 3 

258. 2 



27 

54. 4 

81.7 

121.4 

178.7 

2.59. 7 



28 

55. 2 

82.7 

122. 6 

180.0 

261.2 



29 

50.0 

s : i .7 

12; i . 8 

ISl.-l 

202.7 



30 

. lO . S 

HA . 7 

125. 0 

182. 7 

264.2 

376. 9 



57.0 

85. 0 

120.2 

1.84.0 

205.7 

378. 5 


32 

58. 3 

80.0 

127.3 

185.4 

207. 2 

380. 1 


33 

59. 1 

87. 5 

128.5 

186.7 

208. 6 

.381.7 


34 

59.8 

88 . 5 

129.0 

188.0 

270. 1 

383.3 


3.) 

60. 0 

89.4 

130.7 

189.3 

271.5 

384.9 


36 

61.3 

90.3 

131.8 

190.6 

273. 0 

386.5 


37 

02.0 

91.2 

132.9 

191.9 

274.4 

388.1 


38 

02.7 

92. 1 

1 : 34.0 

193.1 

275.8 

389. 0 


39 

03.4 

93.0 

13.5.0 

194.4 

277.2 

391.2 



CA.l 

93.9 

1.30. 1 

195. C 

278.0 

392.7 

547.0 


04.8 

94.8 

137. 1 

196. 8 

280.0 

394.2 

.548. 6 


05.5 

95. 0 

138.2 

198. 1 

281.4 

395.8 

.5.50. .3 


00.2 

96.5 

1 : 39 . 2 

199.3 

282.8 

397.3 

551.9 

44 

60.9 

97.3 

140.3 

200.5 

284. 2 

398.8 

553.5 

45 

07.0 

98.2 

141.3 

201.7 

285.5 

400.3 

555. 1 


08.2 

99.0 

142. 3 

202.9 

280.9 

401.8 

5.56. 7 


08. 9 

99.9 

14 : 3.3 

204. 1 

288.2 

4 a 3.3 

558.3 

48 

09.5 

100. 7 

144.3 

205.3 

289, 0 

401.8 

559.9 

49 

70.2 

lUl. 0 

145. 4 

206.5 

290.9 

406.2 

561.5 

50 

70 8 

102.4 

146.4 

207. G 

292.2 

407.7 

56.3.1 

51 

71.4 

103.2 

147.4 

208 8 

293. 5 

409. 2 

564.7 

.52 

72.1 

104.0 

148.3 

209.9 

294.8 

410.6 

.560. 3 

53 

72.7 

104,8 

149.3 

211.0 

290. 1 

412.1 

507. 8 

54 

7.3.4 

105. 6 

150.2 

212.2 

297.4 

413.5 

509. 4 


74.0 

106.3 

151.2 

213. 3 

298.7 

411.9 

570.9 


74.6 

107.1 

152.1 

211. 1 

,300.0 

416.3 

572.4 


7.5.2 

107.9 

153.1 

215.6 

.301. 3 

417.7 

574.0 


7.5.8 

108.7 

161.0 

216. 7 

302. 0 

419. 1 

575. .5 


70.4 

109.4 

155. 0 

217.8 

303.8 

420.5 

577.0 


77.0 

110.2 

15.5. 9 

218.9 

305.1 

421.9 

578.0 


'Pahle 29. — Degrees Fahrenheit into degrees eenligrode. 


•F 

” C . 

°V. 

' F . 

“ C . 

• F . 

!• 

1'. 

31 

-0.56 

33 

66 

18.89 

— 2 

.1 

0. 06 

.32 

.00 

:« 

67 

10.44 

- 3 

.2 

.11 

3:1 

..56 

31 

68 

20.00 

- 4 

.3 

.17 

34 

1. 11 

30 

69 

20.56 

- 5 

.4 

.22 

35 

1.67 

29 

70 

21.11 

- 6 

.5 

.28 

36 

2.22 

28 

71 

21,67 

- 7 

.6 

.33 

37 

2.78 

27 

72 

22. 22 

- 8 

.7 

.: i 9 

38 

3. .33 

26 

7.3 

22.78 

- 9 

.8 

.44 

39 

3.89 

25 

74 

23. .33 

-10 

.9 

.50 

40 

4.44 

24 

75 

23.89 

-11 

1.0 

..56 

41 

5.00 

2.3 

76 

24.44 

-12 

1.1 

.61 

42 

5. .56 

22 

77 

25.00 

- 1.3 

1.2 

.67 

43 

6.11 

21 

78 

25.56 

-14 

1.3 

.72 

44 

6.67 

20 

79 

26.11 

—15 

1.4 

.78 

45 

7.22 

19 

80 

26.67 

-16 

1.5 

.83 

46 

7.78 

18 

81 

27.22 

-17 

1.6 

.89 

47 

8. .33 

17 

82 

27. 78 

-18 

1.7 

.94 

48 

8.89 

16 

83 

28.33 

-19 

1.8 

1.00 

49 

9.44 

15 

84 

28.89 

-20 



.50 

10.00 

14 

85 

29. 44 

-21 



51 

10. .56 

13 

m 

30. no 

-22 



52 

11.11 

12 

87 

30. .56 

-23 



5^1 

11.67 

11 

88 

31. 11 

-2-1 



54 

12.22 

10 

89 

31. 67 

—25 



55 

12. 78 

9 

90 

32. 22 

-26 



56 

13. 33 

H 

91 

32.78 

-•27 



57 

1 : 5 . 89 

7 

92 

33. 33 

-■28 



58 

14.44 

6 

93 

89 

-■29 



59 

15.00 

5 

94 

34.44 

-30 



60 

15.56 

4 

95 

35.00 

-31 



61 

16. 11 

3 

9 »i 

.35.56 

-32 



62 

16.67 

0 

97 

;36. 11 

-33 



63 

17.22 

1 

98 

36. 67 

-■34 



64 

17. 78 

0 

99 

37. 22 

-35 



65 

18.33 

— 1 

100 

1 

37.78 

-36 

1 



Table 30. — Miles per hour into meters per second. 


m . 

p . h . 

m - 

p . s . 

m . 

p . h . 

m . 

p . s . 

1 1 

1 

m . 

p . s . 

m . 

p . h . 

m . 
p . s . 

1 

. 45 

19 

8.5 

37 

16.5 

55 

24.6 

2 

.89 

20 

8.9 

38 

17.0 

56 

25.0 

3 

1.3 

21 

9.4 

39 

17.4 

57 

25.5 

4 

1.8 

22 

9.8 

40 

17.9 

58 

25.9 

5 

2.2 

23 

10.3 

41 

18.3 

.59 

26.4 

6 

2.7 

24 

10.7 

42 

18.8 

60 

26.8 

7 

3.1 

25 

11.2 

43 

19.2 

61 

27.3 

8 

3.6 

26 

11.6 

4-1 

19.7 

62 

27.7 

9 

4.0 

27 

12.1 

45 

20.1 

63 

28.2 

10 

4.5 

28 

12.5 

46 

20.6 

54 

28.6 

11 

4.9 

29 

13.0 

47 

21.0 

65 

29.1 

12 

5.4 

30 

13.4 

48 

21.5 

66 

29.5 

13 

5.8 

31 

13.9 

49 

21.9 

67 

30.0 

14 

6.3 

:32 

14.3 

.50 

22.4 

68 

30.4 

15 

6.7 

33 

14.8 

51 

22.8 

69 

30.8 

16 

7.2 

34 

15.2 

52 

23.2 

70 

31.3 

17 

7.6 

35 

15.6 

53 

23.7 



18 

8.0 

30 

10.1 

51 

21.1 




Table 31. — Inches into millibars. 


Inches . 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

009 

29.0 

982.1 

982.4 

982.7 

98.8.1 

983.4 

983.7 

984.1 

984.4 

984.8 

98.5.1 

29.1 

85.4 

85.8 

86. 1 

86.6 

86.8 

87.1 

87.5 

87.8 

88.2 

88.6 

29.2 

88.8 

89.2 

89.5 

89.8 

90.2 

90.6 

90.9 

91.2 

91.5 

91.9 

29.3 

92.2 

92.6 

9'2.9 

93.2 

93.6 

93.9 

94.2 

94.6 

94.9 

95.3 

29.4 

9,5.6 

95.9 

96.3 

96.6 

97.0 

97.3 

97.6 

98.0 

98.3 

98.6 

29.5 

999.0 

999.3 

999.7 

1,000.0 

1,000.4 

1,000.7 

1,001.0 

1,001.4 

1,001.7 

1, 002. 0 

29.6 

1,002.4 

1, 002. 7 

1, 003. 1 

03.4 

03.7 

04. 1 

04.4 

04.7 

05. 1 

05.4 

29.7 

0.5.8 

06. 1 

06.4 

08.8 

07.1 

07.5 

07.8 

08.1 

08.5 

08.8 

29.8 

09.1 

09.5 

09.8 

10.2 

10.5 

10.8 

11.2 

11.5 

11.9 

12.2 

29.9 

12.5 

12.9 

13.2 

13.5 

13.9 

14.2 

14.6 

14.9 

15. 2 

15.6 

30.0 

1,01.5.9 

1,016.3 

1,010.6 

1,016.9 

1,017.3 

1,017.6 

1,018.0 

1,018.3 

1,018.6 

1,010.0 

30.1 

19.3 

10.6 

20.0 

20.3 

20.7 

21.0 

21.3 

21.7 

22.0 

22.4 

30.2 

22. 7 

23.0 

23.4 

23.7 

24.0 

24.4 

24.7 

2.5.1 

25.4 

25.7 

30.3 

26.1 

26.4 

26.8 

27.1 

27.4 

27.8 

28. 1 

28.4 

28.8 

29.1 

30.4 

29.5 

29.8 

30.1 

30.5 

30.8 

31.2 

31.5 

31.8 

32.2 

32.5 

30.5 

1,032.0 

1,033.2 

1,033.5 

1,033.9 

1, 034. 2 

1, 034. 5 

1, 0.84. 9 

1,035.2 

1,035.0 

1,035.9 

30.6 

36.2 

36.6 

30.9 

37.3 

37.6 

37.9 

38.3 

38.6 

38.9 

39.3 

30.7 

39.6 

40.0 

40.3 

40.6 

41.0 

41.3 

41.7 

42.0 

42.3 

42.7 

30.8 

43.0 

43.3 

43.7 

44.0 

44.4 

44.7 

45.0 

45.4 

45.7 

40. 1 

30.9 

46.4 

46.7 

47.1 

47.4 

47.8 

48.1 

48.4 

48.8 

49.1 

49.5 


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